3934 Surprise by Alberich

This was a neat Listener puzzle. With a single theme and sound clues it was fairly straightforward, once the modification was known. The initial letters of the extra words, in clue order, gave "A turn-up for the books", which explained the title. It was then a case of inverting the abbreviations of Biblical books in down entries. The primary reference gives a useful list of these. Jumbling the across entries was made slightly easier since multiple unches had to be the same letters.

Extra words in across clues are shown by square brackets.

1 [Assistant] covers initially naked female with a sheet hurriedly brought round (10)
ENSHEATHES N (initial of naked) + she in anag. sheet
11 It may be provided for shy company head taking on [troublesome] officer (7)
COCONUT C.O. in CO (company) + NUT Ref. coconut-shy
12 For Listener [uninitiates], maximum annoyance (5)
PIQUE sounds like peak
14 Violently set about count acting like [rock] star (8)
STELLATE TELL + A (acting) in anag. SET
15 Revenue in recession [never] lowest round about Christmas (6)
TAXMEN NET reversed round A (about) XM
16 Dutch leaders of European [Union] mull over protest (4)
DEMO D + first letters E M O
17 Woman gives up new Times [puzzle] (4)
19 Confirm bar fellow poured very short [fluid] measure (6)
MICRON anag. CONFIRM minus F (fellow)
21 Uncle's beginning to nag [old] girlfriend to correct errors (8)
EMENDATE EME + N + DATE (girlfriend)
24 Chemical waste principally from chimney in hospital [radiology] department (8)
EFFLUENT F (initial of from) + FLUE (chimney) in ENT (ear, nose & throat)
26 Is excited about new solutions for [traumatic] shock treatment (6)
RINSES rises (=is excited) round N (new) here shock refers to a shock of hair!
27 Unfashionable [horsehair] fabric (4)
LAME 2 Meanings with the accent in Lamé ignored, as is usual in most Listener puzzles, not forgetting cedillas.
29 [Enthusiastically] sharpen garden tool without reason ultimately (4)
HONE N (last letter of reason) in HOE
31 Associate's entertained by British railway [buffs'] club (6)
BRASSY ASS (associate) in B Ry (railway)
33 Overturns drinking bowls containing glue [oddly] (8)
34 Scots force captures most of gun [outfit] making continuous sound (5)
35 Nicked the video, carelessly leaving behind old [keepsake] (7)
THIEVED Anag. the video minus O (old)
36 Financial officials half-heartedly confirm [slump] in Turkey's beginning to spiral (10)

Abbreviations of Biblical books are shown in square brackets. In the grid these are reversed.

2 Queen gets vote as appropriate (5)
ANN[EX] (Queen) ANNE + X
3 Skirt and cape concealing a bit of Elizabeth's enormity (8)
HU[GEN]ESS Hug + E (bit of Elizabeth) + Ness
4 Mass in many parts? Composer's no learner (4)
[HOS]T Ho(L)st
5 Non-European country needs one million at once (6)
STA[TIM] Stat(e) + 1 M
6 Joints supplied by Premier League? (8)
TO[PS]IDES Top sides (teams?)
7 Measure scale of acidity in water (4)
8 Crystal's given to a girl (6)
NI[COL]A Nicol + A
9 Young fast runner's skilful, but not caught on film (7)
[LEV]ERET (C)lever + ET
10 Fat perhaps puts a model in awkward position (10)
13 Accept a singer for dance (10)
PAS[SAM]EZZO Pass a Mezzo
18 Overflowing river leaves tundra in Norway devastated (8)
INUN[DAN]T anag. Tundra (less R) + IN + N (Norway)
20 University men worked out price, being good at maths (8)
[NUM]ERATE Anag. U + MEN + Rate
22 Anglo-Latin firm published Islamic scripture (7)
AL[COR]AN AL + Co. + ran
23 Positive about Hawaii? It indicates a liking (6)
25 After second part of Metamorphoses, Greek goddess abandons love for young Greek
male (6)
EP[HEB]E E (second letter in Metamorphoses) + Phoebe (minus E)
28 Independence lost from popping Valium is looked on with disapproval (5, two words)
[MAL] VU anag. Valium minus I (Independence)
30 Mineral present in ceramic articles (4)
[MIC]A Hidden
32 River is rising in Iceland (4)
[IS]IS is (rev.) in IS This ought to have been entered SISI if the preamble had not warned about "a consistent SINGLE modification.