Across:
8 Record (POTATO) by Queen? (POTATO),
9 Try out (TEST) switch (= reverse indicator) but (but = TUB-) use terminal (‘usE’ terminal = -E) (TEST TUBE) employed by the laboratory (TEST TUBE),
10 Amusingly dishes out mains (‘amusingly’ dishes out/ without ‘mains’ = ugly = UGLY) and it’s not pretty (UGLY),
11 Is this what plagiarists are expected to do (COPY EDITOR) working for the advertising company? (COPY EDITOR),
12 Mediterranean (Mediterranean SEA-) is so (-SO-) named (-N) (SEASON) in winter (SEASON),
14 Former (SOMETIME) Tommies (Tommies = SOMETIM-) travelling (= anagram indicator) to Spain (-E) (SOMETIME),
15 Before Spring (winter) loses the head (w) (‘winter’ without ‘w’ = INTER-) – fickle type (-CHANGEABLE) (INTERCHANGEABLE) is one of those who can go either way (INTERCHANGEABLE),
18 Exchanged (SWITCHED) intelligence (-WIT-) with Charlie (-C-) in storage facility (shed = S-HED) (SWITCHED),
20 Created a stink (REEKED) as had the bang of Benjy (REEKED),
22 He is let out? (he is let out) Solution (= anagram indicator) (he is let out = SILHOUETTE) – trace! (trace = SILHOUETTE),
24 King Cobra has no groin (‘King Cobra’ has no ‘groin’ = kcba = BACK) or spinal column (BACK),
25 Maintain distance perhaps (KEEP STEP) from castle (KEEP) raising (= reverse indicator) dogs and cats (pets = STEP) (KEEP STEP),
26 Director (-D-) in steel (steel) works (= anagram indicator) (steel = EL-EST) (ELDEST) is the first to arrive (ELDEST).
Down:
1 Endless (m) gum (‘gum’ without ‘m’ = -GU-) swallowed by old revolutionary (Wolfe Tone = TON-E) (TONGUE), in a manner of speaking (TONGUE),
2 Don is out of boyband (‘Don’ is out of ‘boyband’ = byba = BABY) – presumably he took to the bottle? (BABY),
3 Is capable of fiery outbursts (VOLCANIC) knocking back (= reverse indicator) most of (e) the garlic (‘clove’ without ‘e’ = clov = VOLC-), cutting the head (p) in a frenzy (‘panic’ without ‘p’ = -ANIC) (VOLCANIC),
4 Closes 25 across (closes ‘keep ‘step’ = STEP) to dance movement (STEP),
5 Sweetheart (‘swEet’ heart = E-) meets (meets) up (= reversal indicator) (meets = -STEEM) (ESTEEM) for appreciation (ESTEEM),
6 Stumble (-TRIP-) going for drink (-TEA-) in ship (SS = S-S) approaching Point (compass point East = -E) (STRIPTEASE) – the one that is alluringly taking off (STRIPTEASE),
7 A (A-) bad start (‘Bad’ start =-B-) is typical (-NORMAL) (ABNORMAL) of eccentric (ABNORMAL),
13 Worries (sweats = SWEAT-S) about school (-S-) dance (-HOP-) (SWEATSHOPS) in exploitive places with no work ethics (SWEATSHOPS),
14 Act as a substitute (PROP) for prop (STAND),
16 Novel (NEW-) might need to be developed (site = -S ITE-) by Frenchman (Monsieur = -M) (NEWS ITEM) from The Irish Times, for example (NEWS ITEM),
17 Adam perhaps (GARDENER from Garden of Eden) is in on the plot (GARDENER),
19 Hangs around (HAUNTS) for hotel (H-) worker’s (workers = ants) speech (= homophone indicator) (‘ants’ = ‘aunts’ = -AUNTS) (HAUNTS),
21 Pardon (EXCUSE) old partner (EX-) taking empty (r) oath (‘curse’ without ‘r’ = -CUSE) (EXCUSE),
23 Genre (TYPE) of work synonymous with The Office (TYPE),
24 Limits betting odds (limits ‘BEtting odDS’ = BEDS) for those fond of the naps (BEDS).