Across:
1 Secret (CLASSIFIED) policeman (Detective Sargent = -DS) follows (= positional indicator) a (A-) (CLASSIFIED ADS) number of those filling columns in the newspaper who are dealing perhaps (CLASSIFIED ADS),
10 Folk tales (LORE-) by Garland (garland = -LEI) (LORELEI) linked to seductive rock music perhaps (siren on the LORELEI rock said to sing to lure sailors to destruction),
11 It’s out of order and director is responsible for it (PREQUEL) and fills in the backstory (PREQUEL),
12 Control (control = STEM) on both sides of stereo system (both sides of ‘stereo system’ = STEM),
13 The outstanding quality (CLASS) on all sides today (CLASS on four sides of today’s grids),
15 Bird’s (birds = EMUS) mysterious (= anagram indicator) Muse? (Muse = EMUS),
17 Fleece producer (EWE) consumed by loungewear (consumed by ‘loungewear’ = EWE),
19 Check (STYMIE) ties? My (ties my = STYMIE) clobber! (= anagram indicator),
21 Hold up (rob = BOR-) revolutionary (= reversal indicator) column (-ROW) (BORROW) by local bum (local ‘bum’ = BORROW),
22 20 down (‘eye’ = EYE-) is upset (-SORE) (EYESORE) by something ugly (EYESORE),
23 Set free (RESCUE) or twist (= anagram indicator) secure (secure = RESCUE),
25 Fix (= anagram indicator) fault (fault = A-TFUL) around resistance (-R-) (ARTFUL) – that’s clever (ARTFUL),
27 Mischief-maker (IMP) discovered in Blenheim Palace (discovered in ‘Blenheim Palace’ = IMP),
29 Goes around getting the job done (goes around ‘getting the job done’ = GENE) – it’s a character builder (GENE),
30 Kind of manual (USERS manual) for Draft-dodging fraudsters (“draft” dodging “fraudsters”
users = USERS),
31 Most of the draft (most of ‘write’ = WRIT) is coming from the court (WRIT),
34 Soul hit (soul hit = LOUTISH) produced by (= anagram indicator) ill-mannered type (LOUTISH),
35 A cat flu (a cat flu = FACTUAL) treatment (= anagram indicator) – you couldn’t make that up! (FACTUAL),
36 Family (CLASS) break (INTERVAL) (CLASS INTERVAL) divides Irish and English, for example (divides Irish and English = CLASS INTERVAL).
Down:
2 Clear (clear = LARCE-) Yank (= anagram indicator) linked to New York (-NY) (LARCENY) robbery (LARCENY),
3 Content of mausoleum (content of ‘mausoleum’ = -SOLE) in part of Wellington (SOLE of Wellington),
4 DNA removed from Icelandic (‘DNA’ removed from ‘Icelandic’ = icelic = ICICLE) spike that’s frozen (ICICLE),
5 Take advantage of (IMPOSE) introduction to inherently (introduction to ‘inherently’ = I-) bad (= anagram indicator) poems (poems = -MPOSE) (IMPOSE),
6 Lighten up perhaps (DIET) and take the figs out of digestif (take the “figs” out of “digestif” = diet = DIET),
7 Spirit (-RUM-) and medium (-M-) protected by the German (the = D-ER) (DRUMMER) down in the pit (DRUMMER in orchestra pit),
8 Students (CLASS) have a problem (STRUGGLE) (CLASS STRUGGLE) getting this concept in political philosophy (CLASS STRUGGLE),
9 Best come out first (CLASS WILL TELL) to suggest those getting taught a lesson can’t keep a secret (CLASS WILL TELL),
14 Remarkable (AWESOME) tops on a white elephant (tops on ‘a white elephant’ = AWE-) – the number is unspecified (-SOME) (AWESOME),
16 Eurosceptic dismisses soccer (‘Eurosceptic’ dismisses ‘soccer’ = eupti = TIE-UP) association (TIE-UP),
18 How to get out of Sherwood (‘how’ to get out of ‘Sherwood’ = serod = DOERS) with industrious group (DOERS),
20 Some Berkeley educator (some ‘Berkeley educator’ = EYE) from Faculty of Sight (EYE),
21 Some swear blind (some ‘swear blind’ = arb) – backtrack (= reversal indicator) (arb = BRA) provides support to a woman (BRA),
24 Sustainable without a bit (‘sustainable’ without ‘a bit’ = susanle = SENSUAL) of passionate gratification (SENSUAL),
26 Mural of (mural of = FORMULA) revolutionary (= anagram indicator) with instructive set of words (FORMULA),
27 Mishit (mishit = ISTHMI) shot (= anagram indicator) in Panama and others (ISTHMI),
28 Benefit (PROFIT) to university worker (PROF-) getting it (-IT) (PROFIT),
32 Delves into (DIGS) extremes of director’s shortcomings (extremes of ‘director’s shortcomings’ = DIGS),
33 Characters regurgitated (= reversal indicator) in Bergerac, Spooks (in ‘Bergerac Spooks’ = racs = SCAR) will mark you for life (SCAR).