S by Hedge-sparrow

This week Hedge-sparrow gave us a fine puzzle packed full of thematic features. Unclued answers were EVOLUTION, GALAPAGOS and (Charles) DARWIN, whose bicentenary fell this year. The answers to the four normal clues had to be jumbled before entry into the grid, which Gregson took as symbolising genetic recombination. Clashes in the grid had to be resolved by considering the message from extra letters in wordplay in Across answers, namely SURVIVAL OF THE FITTEST. So, where letters clashed, solvers had to select the letters of THE FITTEST to appear in the grid, always creating new words in place of the clashing answer. Extra letters in the wordplay of all but the last six Down answers spelt out THE VOYAGE OF THE, which led to BEAGLE being highlighted in the grid. Finally, the last six extra letters were P,P,P,A,A,A, and these had to replace DARWIN in the grid. This left a 3 by 6 array spelling out APE, APT, OPT, OAT, MAT and MAN, showing the evolution of APE to MAN by changing one letter at a time, which provided a satisfying finish to an enjoyable puzzle. The title, S, was a cryptic indication of The Origin of Species, Darwin’s most famous work.

Extra letters in wordplay are indicated by [].

1 Unclued (9)
11 Child leading the way, once, in a manner of speaking (4)
[S]ONST SON (Child) + ST (street ie way)
13 Redesign league badge (5)
[U]EAGLE Anagram of LEAGUE
14 Butler discarding fag-end in Romanian capital (3)
LE[R]I BUTLER less BUT (fag-end), + I’ (in)
15 Flatter WC concealed in wood beside river (7)
PLA[V]INER LAV (WC) inside PINE (wood), + R (river)
17 Short entertainer beginning to mutter a rhetorical phrase (5)
COM[I]MA COMIC (entertainer), less last letter, + M (first letter of MUTTER) + A
18 Fix day to take effect in Spain (7)
D[V]ESTINE D (Day) + VEST (to take effect) + IN + E (Spain)
19 Queen drove through Iowa (4)
RANI[A] RAN (drove through) + IA (Iowa)
20 Arab socialists - believers rejecting what's central to creed, following false god (9)
BAA[L]THISTS THEISTS (believers), less E (middle letter of CREED) after BAAL (false god)
21 Swear at boy (4)
24 Absent two weeks (with no time for sleep) in command of vessel (6)
A[F]ORTIC A (Absent) + FORTNIGHT (two weeks) less NIGHT (time for sleep), + I/C (in command)
27 Abundance in the Highlands comes on the back of great progress (6)
G[T]ROWTH ROWTH (Scottish word for “abundance”) after GT (great)
30 Sums Academician gave as a gift to high school (4)
ADD[H]S A (Academician) + DD (gave as a gift) + HS (high school)
32 Metalworker to strike hot grating initially (9)
IRONSMIT[E]H SMITE (to strike) + H (hot) after IRON (grating, adjective)
35 "Pedal A" - note coming after sforzando measure (4)
S[F]PAN P (Pedal) + A + N (note), all after SF (sforzando)
37 Denounce kidnapping of Detective Inspector by violent conmen (7)
COND[I]EMN DI (Detective Inspector) inside CONEMN (anagram of CONMEN)
39 Bag contains a coloured bit of rare shellfish (5)
NACRE[T] A + C (coloured) + R (first letter of RARE), all inside NET (bag)
40 Disturb nesting quarter for more than one 13, perhaps? (7)
[T]ENSIGNS Anagram of NESTING, + S (South ie quarter)
A quarter being any point of the compass
41 Seaweed entangling end of undersea stirring-pole (3)
OAR[E] ORE (Seaweed) containing A (last letter of UNDERSEA)
43 Force leader of Tories into retracting pamphlet (5)
TEETH[S] T (First letter of TORIES) inside SHEET (pamphlet), reversed
44 Move rapidly after a month in Israel (4)
ADAR[T] DART (Move rapidly) after A
45 Unclued (9)

1 A large number beginning to leave as raunchy drama's starting - Shakespearean "Grease" (6)
[T]ENLARD TEN (A large number) + L (first letter of LEAVE) + A,R,D (first letters of AS RAUNCHY DRAMA)
2 Way active virus arises (3)
VI[H]A A (active) + HIV (virus), reversed
3 An image missing top of chorister's head (5)
ON[E]ION ONE (An) + ION (image) less C (first letter of CHORISTER)
4 Imminent return of Old Left persuading Member to drop down a place (7)
LOOM[V]ING O (old) + L (Left), reversed, + MOVING (persuading), with M (Member) moving by one place
5 Fruit juice on tap? Very nearly! (6)
SAPOTA (jumbled before entry) SAP (Juice) + O’ (on) + TAP, less last letter
6 Bundle abstainer into trunk (6)
BOTTLE (jumbled before entry) TT (Abstainer) inside BOLE (trunk)
7 End, at length, bitterness (4)
G[O]ALL GOAL (End) + L (length)
8 End up wasting time supporting Attorney-General? Acknowledged! (7)
AG[Y]NISED DESTINY (End) less T (time), underneath AG (Attorney-General)
9 Flashed Edmund's torch to provide basis for information about luminance (7)
GLENTE[A]D TEAD (Spenserian word for “torch”) under GEN (information) containing L (luminance)
10 Zoroastrian in Iran (not Britain) takes on extremely silly unorthodox belief (6)
[G]HERESY GHEBER (Zoroastrian in Iran) less B (Britain) + SY (first and last letters of SILLY)
12 Extracting core of identification code's senseless (4)
NUMB[E] E-NUMBER (identification code) less first and last letters
16 Row Kirkpatrick's vessel (3)
[O]ARK OAR (Row) + K (Kirkpatrick)
18 Unclued (6)
22 Florida eager to associate with Democrat wearing short cassock (7)
[F]APRONED FA (Florida) + PRONE (eager) + D (Democrat)
23 Hunter's horn call heralds violent attack when satellite comes down (7)
MO[T]ONSET MOT (Hunter’s horn call) + ONSET (violent attack)
25 Spanish mansion houses tea plant from America (7)
CASC[H]ARA  CASA (Spanish mansion) containing CHAR (tea)
26 Satisfactorily twin French and English cities (6)
NICE[E]LY NICE + ELY (French and English cities)
28 Lash German sheep (6)
GAMMON (jumbled before entry) G (German) + AMMON (sheep)
29 Wait for at the finish (6)
ATTEND (jumbled before entry) AT + T’ (the) + END (finish)
31 County employees take on private secretary (6)
STAFF[P]S STAFF employees) + PS (private secretary)
33 Depression giving rise to sharp intake of breath (3)
[P]SAG GASP (sharp intake of breath), reversed
34 Expression of disgust by Australian following end of match - that's a laugh! (4)
H[P]AHA PAH (Expression of disgust) + A (Australian), all after H (last letter of MATCH)
36 Spur for riding horse (5)
PRON[A]G PRO (for) + NAG (horse)
38 Bar leading lady who's on Ecstasy (4)
DIV[A]E DIVA (leading lady) + E (Ecstasy)
42 Woman dean, regularly turning up, creating trouble (3)
AD[A]O Alternate letters of wOmAn DeAn, reversed