Across:
8 She leaves osteopath (“she” leaves “osteopath” = otopat = POTATO) for Spud (POTATO),
9 Eats a rum (eats a rum = AMATEURS) fudge (= anagram indicator) produced by novices (AMATEURS),
10 Part of the Sci-Fi’s hypothesis (part of the “Sci-Fi’s hypothesis” = FISH) produced by the group in school (school of FISH),
11 In a manner of speaking, English (KENTISH-) workers (-MEN) (KENTISHMEN) from Canterbury and Maidstone living in south east England (KENTISHMEN),
12 What do you make of 10 across (make SCAMPI with ‘fish’) – is it something fishy? (SCAMPI),
14 Is under an obligation (BEHOLDEN) to be (‘be’ = ‘bee’ = BE-E-) heard (= homophone indicator) locking up part of the vessel (-HOLD-) that’s new (-N) (BEHOLDEN),
15 Makes an impression (REGISTERS) on 5 down (“parish” = PARISH) heading (= positional indicator) (PARISH REGISTERS) for local records (PARISH REGISTERS),
18 Left (L-) the top off (w) timepiece (‘watch’ without ‘w’ = -ATCH) – it’s crucial (-KEY) (LATCHKEY) for getting into the internal housing (LATCHKEY),
20 Bitter type from kitchen garden (ENDIVE) envied (envied = ENDIVE) cook (= anagram indicator),
22 Mince (GROUND BEEF) is base (GROUND) for most of 14 down (‘beefy’ = BEEF) (GROUND BEEF),
24 It’s tokenism dismissing ties (‘tokenism’ dismissing ‘ties’ = oknm = MONK) to one of them in The Abbey (MONK)
25 Concealing (STASHING) fraudulent enterprise (sting = ST-ING) outside? Academy (-A-) is calling for silence! (-SH-) (STASHING),
26 Finishes with 13 down (‘main course’ = COURSE) in college (COURSE).
Down:
1 Sets-up (= reversal indicator) firm (Co = O-C) incorporating assistance (aid = -DIA-) from foundation in Biarritz (foundation in “Biarritz” = Z-) (ZODIAC) for those making predictions (ZODIAC),
2 What do you make of 8 across (make MASH of ‘potato’) in Pulp? (MASH),
3 24 across (‘monk” = MONK-) and 10 across (‘fish’ = -FISH) (MONKFISH) on a seafood diet perhaps (MONKFISH),
4 Opens 13 down (‘main course’ = MAIN) in primary (MAIN),
5 Harp is (harp is = PARISH) drunk (= anagram indicator) in father’s district (PARISH),
6 That medley (that medley = METHYLATED) played (= anagram indicator) with type of spirit (METHYLATED spirit),
7 Release (FREE) one of those behind bars? (BEER) (FREE BEER) Presumably, there’ll be no charges for drinking this on premises after hours perhaps! (FREE BEER),
13 Principal (MAIN) has a series of lessons (COURSE) (MAIN COURSE) for those in Home Economics to learn (MAIN COURSE),
14 Muscular type (BEEFY) of bachelor (B-) knocks back (= reversal indicator) most of the (d) food (‘feed’ = ‘deef’ without ‘d’ = -EEF-) by the end of the day (the end of ‘day’ = -Y) (BEEFY),
16 Eagerness (ALACRITY) for American (A-) credit (-CR-) in volatile (= anagram indicator) Italy (Italy = -LA-ITY) (ALACRITY),
17 Essentially (IN EFFECT), head chef (head ‘chef’ = -C-) consumed by Fifteen (fifteen = IN EFFE-T) (IN EFFECT) somehow (= anagram indicator),
19 Tease (KID-) director (-D-) from Ireland (Ireland domain = .ie = -IE) (KIDDIE) of The Child (KIDDIE),
21 Get away (VANISH) from non-achievers not getting encore (‘non-achievers’ not getting/without ‘encore’ = nahivs = VANISH),
23 Broody Sultan produces them (Broody Sultan chicken produces EGGS) for horse (-GG-) in point-to-point (east + south = E-S) (EGGS),
24 Sling out of Mulligan’s (‘sling’ out of ‘Mulligans’ = mula = MAUL) bash locally (MAUL).