Across:
1 Associate scratched toe ('associate' scratched 'toe' = asscia = CASSIA) by medicinal shrub (CASSIA),
4 Spoilt (PAMPERED) by spinning (= reverse all indicator) the German (‘the’ German = der = -RED) record (Extended Play record = EP = -PE-) – a favourite of The Tourists (map = PAM-) (PAMPERED),
9 Opening 18 across (opening ‘judge and jury’ = (JUDGE -) to end taxes (end ‘taxeS’ = -S) (JUDGES) and rates (JUDGES),
10 Wild (= anagram indicator) toucans (toucans = AC-OUNTS) enveloping front covers (front ‘Covers’ = -C-) (ACCOUNTS) of books (ACCOUNTS),
12 One with potential (LIKELY LAD) providing odds on (odds-on = LIKELY) one in those in the stable (stable LAD) (LIKELY LAD),
13 Play with matches (tennis), striking the first (t) (‘tennis’ without ‘t’ = ENNIS) in Irish town (ENNIS),
14 Welcome (RECEPTION-) to sit (sit) roughly (= anagram indicator) (sit = -IST) (RECEPTIONIST) in the office answering the phone (RECEPTIONIST)
18 Law partners presumably making all the decisions (JUDGE AND JURY) in a kangaroo court perhaps (JUDGE AND JURY),
21 Headless (p) units of wisdom (pearls of wisdom) (‘pearls’ without ‘p’ = EARLS) from peers (peers = EARLS),
22 Exaggerate (COLOUR-) flu (flu) spreading (= anagram indicator) (flu = -FUL) (COLOURFUL) out of the blue, for instance (COLOURFUL),
24 Bit players (extras = EXTRA-S) holding party (-DO-) (EXTRADOS) for one of those in The Arch (EXTRADOS),
25 Local bananas (MAD-) and grass found at the centre (‘gRASs’ = -RAS) (MADRAS) in old India (MADRAS),
26 Music (ROCK music) on the old boat (sailor = old SALT) (ROCK SALT) synonymous with The Cellar (ROCK SALT / salt cellar),
27 Remove hair from sea urchins (remove ‘hair’ from ‘sea urchins’ = seucns = CENSUS) and count (CENSUS).
Down:
1 Sweet-talkers (CAJOLERS) fixing (= anagram indicator) Joel's car (Joel's car = CAJOLERS),
2 Quit local (-KICK) team (SIDE-) before (= position indicator) (SIDEKICK) associate (SIDEKICK),
3 Yard stick (yardstick = IDEAL) produced from one (I-) wood (-DEAL)? (IDEAL),
5 Can’t dice (can’t dice) chops (= anagram indicator) (can’t dice = ACCIDENT-) for friend (-ALLY) (ACCIDENTALLY) inadvertently (ACCIDENTALLY),
6 Took care of (PROCESSED) writer (-ED) after (= position indicator) operation (PROCESS-) (PROCESSED),
7 Seek office (RUN-) near unfinished (n) public house (inn) (‘inn’ without ‘n’ = -IN-) ahead of some (a head of ‘Some’ = -S) (RUN-INS) engagements (RUN-INS),
8 Call a halt to (DESIST) chap leaving dispatches (‘chap’ leaving ‘dispatches’ = distes = DESIST),
11 Offers lessons to those who want to competently land (FLYING SCHOOL) fish (SCHOOL)? From the start (= position indicator), it’s for the birds (FLYING)! (FLYING SCHOOL),
15 Some old German’s (some old Germans = PRUSSIANS) political leader (‘Political’ leader = P-) found on the shores of the Black Sea, for example (-RUSSIANS) (PRUSSIANS),
16 The going rates for boarders (BUS FARES) or what the old conductors used to ask for (BUS FARES),
17 Those with bikes (CYCLISTS) starting Chapter (starting ‘Chapter’ = C-) on far side of the country (far side of ‘countrY’ = -Y-) for leading criminals (leading ‘Criminals’ = -C-) with records (-LISTS) (CYCLISTS),
19 Polish (polish/varnish = VENEER) film? (VENEER),
20 So-and-so abandons accordionists (‘so-and-so’ abandons ‘accordionists’ = ccriit = CRITIC) for a job on the paper (CRITIC),
23 Country (USA-), for example (e.g. = -GE) (USAGE), brings up (= reverse indicator) the matter of consumption (USAGE).