Across:
8 You and I (us = SU-) review (= reversal indicator) party (-DO-) for returning (= reversal indicator) neighbours (UK = -KU) (SUDOKU) – the difficulty is getting the numbers right (SUDOKU),
9 Court order (-RULE-) to close tavern (to close ‘taverN’ = -N-) in park (PU-T) (PURULENT) relates to one of those in 10 across turning yellow (‘spot’ yellow/pus = PURULENT),
10 Catch sight of (SPOT) The Borders’ tourist traps (the borders ‘TOurist traPS’ = tops = SPOT) coming back (= reversal indicator),
11 Can siestas (can siestas = ASSISTANCE) work (= anagram indicator) for those who need a helping hand? (ASSISTANCE),
12 Half the (half the) criticism (half the ‘REView’ = rev = VER-) falls back (= reversal indicator) on (-ON-) a (-A) (VERONA) city in Italy (VERONA),
14 Sets up (= reversal indicator) agent (rep = PER-) from America (-US-) in (-IN-) government (-G) (PERUSING) taking an interest in the classified documents? (PERUSING),
15 Take a bribe (GIVE THE GAME AWAY) to reveal a secret (GIVE THE GAME AWAY),
18 Illustrations (DRAWINGS) by Batty (= anagram indicator), Darwin (Darwin = DRAWIN-) and Gauss (unit of magnetic induction = -G-) given to Society (-S) (DRAWINGS),
20 Overreacts leaving service station (‘overreacts’ leaving ‘service station’ = sietin = TIE-INS) with promotional links to the films, for example (TIE-INS),
22 Family (TYPE-) with women (-W-) taking holy orders, for example (-RITE-), introducing reform (introducing ‘Reform’ = -R) (TYPEWRITER) essential to the old office (TYPEWRITER),
24 Mount (MARE) concealed in the Panama redwood (concealed in the ‘PanaMA REdwood’ = MARE),
25 Centre of attention (centre of ‘atteNtion’ = -N-) in Ring (chime = CHIM-E-) – yard (-Y-) at school (-S) (CHIMNEYS) provides outlets for the smokers (CHIMNEYS),
26 Haunts (haunts = SUN HAT) complex (= anagram indicator) in Panama (Panama SUN HAT).
Down:
1 Agile figure (SUPPLE figure) takes cars from upper class (takes ‘cars’ from ‘upper class’ = uppels = SUPPLE),
2 Sample of gazpachos tested (sample of ‘gazpacHOS Tested’ = HOST) by entertaining type (HOST),
3 Make a stylish impression on (CUT A DASH) Pierce (pierce/puncture = CUT) and Bill (A D-) in the forest (-ASH) (CUT A DASH),
4 Some characters develop useful (some characters ‘develOP USeful’ = OPUS) work by the artist (OPUS),
5 Treasures a report covering (‘treasuRES A REport’ covering = resare = ERASER) up (= reversal indicator) what on paper whitewashes mistakes (ERASER),
6 A chance for redemption (CLEAN SLATE) with low-fat (-LEAN) salt (salt = SLAT-) made (= anagram indicator) in Clare (C- -E) (CLEAN SLATE),
7 Performing (-ON-) in Canada (Canada = ANAC-DA) playing (= anagram indicator) (ANACONDA) a snaky type (ANACONDA snake),
13 Finished (OVER-) work (-W-) on high (-H-) trees (-ELMS) (OVERWHELMS) in swamps (OVERWHELMS),
14 Egyptians release tiny (‘Egyptians’ release ‘tiny’ = egpas = PAGES) book collections (PAGES),
16 Trim (n) bar (‘inn’ without ‘n’ = IN) is an asset one associates with the singer (RHYTHM) (IN RHYTHM) at the same time (IN RHYTHM),
17 Starter of mushroom (starter of ‘Mushroom’ = M-) risotto (risotto = -OTORIST) prepared (= anagram indicator) (MOTORIST) for one of those getting out of Dodge, perhaps (for one of those getting out of Dodge car perhaps = MOTORIST),
19 New (N-) users (users = -URSES) possibly (= anagram indicator) (NURSES) out of the hospital (NURSES),
21 Complainers have no spice (‘complainers’ have no ‘spice’ = omlanr = NORMAL) as usual (NORMAL),
23 Pilot study (TEST) amidst the white storks (amidst the ‘whiTE STorks’ = TEST),
24 Grey matter (MIND) found on the banks of Mississippi Sound (found on the banks of ‘MIssissippi SouND’ = MIND).