Across:
8 10K (-RUN-) in Belgium (B-E-) won (won) reportedly (= homophone indicator) ('won' = 'one' = -I) (BRUNEI) by Malaysian neighbour (BRUNEI),
9 Jack (CARD) T. Ennis (‘T. Ennis’ = ‘tennis’ = GAME) (CARD GAME) is 21, for instance (‘twenty-one’ = blackjack/pontoon = CARD GAME),
10 It’s not nice (UGLY) starting university (starting ‘University’ = U-) with key (music key -G-) to empty place (‘lAy’ with ‘a’ = -LY) (UGLY),
11 They speak against statement (GAINSAYERS) of profits (gains = GAIN-S) around State (-SAY-) Enterprise ridiculing leaders (‘Enterprise Ridiculing’ leaders = -ER-) (GAINSAYERS),
12 Reviews (= reverse indicator) short (r) broadcast (air) (‘air’ without ‘r’ = ai = -IA) by two accountants (CA + CA = ACAC-) (ACACIA) and one of the Wattles from Australia (ACACIA is a wattle in Australia),
14 Turns up (= reverse indicator), manuscript (ms = -SM) is (is = si = -S-I-) about one (-I-) type of music (rap = PAR-) (PARSIISM) – an Iranian type many have faith in (PARSIISM),
15 Switched sides (CHANGED ONE’S TUNE) on LP – presumably that’s what DJ might have done? (CHANGED ONE’S TUNE),
18 Ran sales (ran sales) organisation (= anagram indicator) (ran sales = ARSENALS) from a number of depots (ARSENALS),
20 Run (-R-) into State (= homophone indicator) Police (‘cops’ = ‘copse’ = CO-PSE) (CORPSE) in the dead centre of the hospital (CORPSE),
22 Perfect place to have breakfast (CEREAL BOWL) in Clare (CE-) with authentic (-REAL) dish (BOWL) (CEREAL BOWL),
24 Concealed in primrose paths (concealed in ‘primrOSE Paths’ = osep) dug up (= reverse indicator) (osep = PESO) in Cuban capital (Cuban capital/money = PESO),
25 They move goods (HAULIERS) for hospital (H-) and university (-U-) in Israel (Israel) all over the place (= anagram indicator) (Israel = -A-LIERS) (HAULIERS),
26 Gets rid of (ERASES) most of those in 5 down (most of ‘eraser’ = ERASE-) for head of state (head of ‘State’ = -S) (ERASES).
Down:
1 Temperature (T-) reflects (= reversal indicator) most of (y) Gary ('garY' without 'y' = gar = -RAG-), Indiana – to begin with ('Indiana' to begin with = -I-), it's cold (-C) (TRAGIC) and dreadful (TRAGIC),
2 Be resentful (ENVY) of English ivy on the borders (‘ENglish iVY’ on the borders = ENVY),
3 Cadger is (cadger is) wrong (= anagram indicator) (cadger is = DISGRACE) and there’s a shame in that (DISGRACE),
4 Sample of the smoothie (ACAI berry used in smoothie drinks) embraced by Maria Callas makes a comeback (= reverse indicator) (embraced by ‘marIA CAllas’ = iaca = ACAI),
5 Cleans up the childish mistakes (ERASER) for Regina (-R-) in flowing (= anagram indicator) saree (saree = E-ASER) (ERASER),
6 A tormentor of 13 down (UGLY SISTER tormentor of ‘Cinderella’) in 10 across (‘ugly’ = UGLY) and 21 down (‘sister’ = SISTER) (UGLY SISTER),
7 Prom is in (prom is in) trouble (= anagram indicator) (prom is in = IMPRISON) with lockdown? (IMPRISON),
13 New start (‘New’ start = -N-) for the German (‘the’ German = -DER-) going to the Spanish (‘the’ Spanish = -EL-) League (-L-) divides agents (CIA = CI-A) (CINDERELLA) in a story of rags-to-riches (CINDERELLA),
14 The positions taken by rugby players (PROPS) and the odd person (odd letters of ‘PeRsOn’ = PRO-) going to park (-P-) beside school (-S) (PROPS),
16 Ran homes (ran homes) refurbished (= anagram indicator) (ran homes = HORSEMAN) by cavalier type, of course (HORSEMAN),
17 Passed (EXCELLED) divorcee (EX-) on the phone from New York (-CELL- phone) to editor (-ED) (EXCELLED),
19 Please (please) boss (= anagram indicator) (please = ASLEEP) out for the night (ASLEEP),
21 Relative (SISTER) removes wall from stairwells (removes ‘wall’ from ‘stairwells’ = stires = SISTER),
23 Remove from office (OUST) holy books (Old Testament = O-T) about America (-US-) (OUST),
24 Lip reader dismisses idler (‘lip reader’ dismisses ‘idler’ = paer = PEAR) from the conference (conference PEAR).