Across:
8 Back (= reversal indicator) one (-I) graduate (BA = -AB-) with motto (motto/saw = WAS-) (WASABI) – a really hot one! (WASABI),
9 Some of the water (HYDROGEN and oxygen make up water) on the top of the table is the first one you’ll see (on the top of the Periodic Table, HYRDOGEN is No 1),
10 Have one’s heart set on (ENVY) responsively releasing spoilers (“responsively” releasing “spoilers” = envy = ENVY),
11 Locate tree (locate tree = ELECTORATE) chopped up (= anagram indicator) by one possibly preparing to change what’s going into the house (ELECTORATE),
12 Pragmatist will have no part (‘pragmatist’ will have no ‘part’ = gmaist = STIGMA) in disgraceful sign (STIGMA),
14 Dry (AIR-) fortified wines (-PORTS) (AIRPORTS) for those in lounges preparing to take flight (AIRPORTS),
15 Major achievement in the end (army major achievement in the end = DECISIVE VICTORY) of a knockout blow (DECISIVE VICTORY),
18 Drunk (= anagram indicator) declines (declines = LICENSED) permission to sell drink (LICENSED),
20 Way-out (gateway = PORTAL) wine (PORT-) to go with a (-A-) light starter (‘light’ starter = -L) (PORTAL),
22 Rugby player (PROP-) is a top lawyer (attorney general = -AG-) and (-AND-) a (-A) (PROPAGANDA) contributor to fake news (PROPAGANDA),
24 Remove from office (OUST) piece of spurious technology (piece of ‘spurious technology’ = OUST),
25 Revolutionary (= anagram indicator) regime (regime = EMIGR-E) seizes a (-A-) time (-T-) (EMIGRATE) to get out of the country (EMIGRATE),
26 Crafty type (art = TRA-) retires (= reversal indicator) from Russian body (Duma) – losing a leader (d) (‘Duma’ losing ‘d’ = -UMA) (TRAUMA) comes as a shock (TRAUMA).
Down:
1 The attractive thing (MAGNET) about (= anagram indicator) agent (agent = -AGNET) following (= positional indicator) Frenchman (Monsieur = M-) (MAGNET),
2 Early man (BABY) is a bundle of joy (BABY),
3 Retail (retail = LITERA-) problem (= anagram indicator) at the opening of trading (opening of ‘trading’ = -T-) for one (-I) (LITERATI) of those consumed by the books (LITERATI),
4 Small (S-) garden implement (-HOE) (SHOE) in Oxford, for one? (Oxford SHOE),
5 Runs daily (EDITOR) and gets to ride to (ride to = EDITOR) work (= anagram indicator),
6 Warning from swinger (warning on golf course = “fore” = “four” = FOUR -) on the radio (= homophone indicator) for Bill (-POSTER) (FOUR-POSTER) – an old retiring type (FOUR-POSTER),
7 Has a will (TESTATOR) to check out (TEST-) extreme atmosphere (extreme ‘atmosphere’ = -A-) on The Hill (-TOR) (TESTATOR),
13 Trialists (GUINEA PIGS) from the old English capital (‘21 shillings’ = a GUINEA equivalent to £1.05) joining the Chester Whites (breeds of PIGS) (GUINEA PIGS),
14 Change (AMEND) name (name = AMEN-) freely (= anagram indicator) by degree (-D) (AMEND),
16 Sally’s (sallies = EPIGRAMS) Oriental (east = E-) farm animals (pig + rams = -PIGRAMS) (EPIGRAMS),
17 Iron Maiden opens (‘iron maiden’ opens = IM-) for The Hothouse Flowers, for example (-PLANTS) (IMPLANTS), with a number of installations in The Theatre (IMPLANTS),
19 It’s a symptom (SIGNAL) of gals in (gals in = SIGNAL) distress (= anagram indicator),
21 Part of overseas sum employed (part of “overseas sum employed” = ASSUME) to take something on (ASSUME),
23 A basic requirement (NEED) of ne’er-do-well dismissing Orwell (‘neer do well’ dismissing ‘Orwell’ = need = NEED),
24 Cover for a lifestyle (cover ‘for a lifestyle’ = ORAL) in a manner of speaking (ORAL).