3978: Symbolism by Wasp

This was a neat puzzle from Wasp. The title explained the theme – SYMBOL IS M! The wordplay in down clues had an extra letter. In order these letters gave the message – ONE LETTER RELOCATED. By moving one letter of some across answers into the unclued down lights you could make MONSIEUR and THOUSAND. By highlighting these two and the hidden word MAIDEN (all represented by M) you could make the shape of a capital M. The initial letters of extra words in the other across clues gave SEBLANCE. Gregson thought that this must be SEMBLANCE (an image?) lacking the thematic M.

Extra words in across clues are shown in bold type and extra letters in wordplay in square brackets.

ACROSS
2 Artist paints scantily clad models around Sweden (11)
LANDSCAPIST anagram PAINTS CLAD + S (Sweden)
10 Mark meets a good man escaping from Italian town (7)
MAGENTA M (mark) + A GENT + À (from)
11 Vehicle with a barely legal instrument (5)
CARTA CART + A
12 Held out in city lodgings (5)
DELHI Anagram HELD + I (in)
13 In Paris, the badge is yellow (5)
LEMON LE (THE in French) + MON (Japanese famiy badge)
14 Rear second deer (5)
HINDS HIND (rear) + S
15 Forget a poet's name (7)
UNLEARN Un (A) + LEAR + N
16 Insect -- female nearly swallows another (6)
MANTIS ANT in MIS(s)
20 Fleshy body's universal luminance in form of radiation (5)
UVULA UL in UVA
21 Perhaps son lives with girl (5)
ISSUE IS (lives) + SUE (that girl’s name)
22 Drains jug on board (6)
SEWERS EWER in SS (steam ship)
25 Ordered engineers to heat house (7)
THEATRE Anagram RE + T (to) + HEAT
28 City exclusive on the radio (5)
SEOUL Homophone SOLE
29 Left port carrying a great deal (5)
LADEN L + ADEN
31 Complete turns in to stop any working valve (5)
DIODE DO (reversed) in DIE
32 Theory about new Louisiana religion (5)
ISLAM LA (Louisiana) in ISM
33 This crystalline mineral species could be formed by developing prerosion (7, two words)
IRON ORE Anagram PREROSION less SP (Species)
34 Care of the most recent alliance in European coinage (11)
NEONATOLOGY NATO in NEOLOGY

DOWN
1 Quantity of corn maybe found in compound -- it's starch (6)
AMYLUM M[o]Y in ALUM
2 Wash deformed navel (4)
LAVE Anagram [n]AVEL
3 Noted succession of new German uncle (5)
NEUME NEU (new in German) + [e]ME
4 Guide needs staying power before end of tour (5)
STEER STEE[l] + R (end of touR)
5 Ed cleans up these days (7)
CALENDS Anagram ED CL[e]ANS
6 Nick's after a hundred dollars win (7)
ACHIEVE A C (hundred) + [t]hieve
7 Colour antique plate with it (5)
PAINT PA[t]IN + ‘t (IT)
8 Post boss's removal sign (7)
STUDDLE STUD + D[e]LE
9 Put bracken around most of betel inlay (6)
TARSIA SI[r](I) in TARA
17 To falsely accuse a sister by herself? (7)
ASPERSE A S[r] PER SE
18 A flower and fruit wrapped in tissue (7)
TELLIMA LIM[e] in TELA
19 I composed Triton's Latin anthem (7)
INTROIT anagram I + TRITON + [L]
21 For the same reason, I hide bird (6)
SISKIN S[O] I + SKIN (HIDE)
23 Drew Indians under control (6)
REELED [C]REE + LED
24 Mythical force carried by a dark old god (5)
WODAN OD in [a] WAN
26 Spa treated thyroid without iodine (5)
HYDRO anagram [T]HYROID less i (iodine)
27 Basque organisation involved with old, old language (5)
TAINO [E]TA + IN + O (old)
30 Roddy cooked fish (4)
DORY anagram RO[D]DY