Solution to 20A has been deliberately left unsolved and is to be answered only by a non-regular / novice commenter, with proper annotation. Those who have answered earlier in the week, please give others a chance.
Open for anyone to answer, if not solved by 1 PM.
ACROSS
8 Committed detectives taking out time for event (8) INCIDENT {IN{+cid-t)CIDENT
9 Like keeping presented plants (6) AGAVES {A{GAVE}S}
11 Test car by turning it on (8) AUDITION {AUDI}{IT+ON}*
12 Mount finest steer (8) BESTRIDE {BEST}{RIDE}
13 No love? Girl's retreating to place like Venice! (6) LAGOON {NO}{O}{GAL}<=
14 Cruelly pick out and turn a man's colon as an illustration (11,4) PUNCTUATION MARK {PICK+OUT+TURN+A+MAN}*
18 So pain reliever works for basic ego! (3,3) ICE BAG {ICE+BAG+SO}*=BASIC EGO
20 Uses one incessantly in works of little consequences (3-5) N?N-?S?U? (Addendum - NON-ISSUE {USES+ONe+IN}* - See comments)
23 Lady's cryptic clues for macho man (8) HERCULES {HER}{CLUES*}
24 Alien trapped in prey's germ cell (6) GAMETE {GAM{ET}E}
25 Company guy makes sense (6) COGENT {CO}{GENT}
26 A right time and one small endeavour leads to creativity (8) ARTISTRY {A}{R}{T}{1}{S}{TRY}
DOWN
1 Charlie kicked right out in full draw (6) ENTICE ENTI(+c-r)CE
2 Water pill - It cured one's suffering (8) DIURETIC {IT+CURED+1}*
3 Genuine pal, Indian holds as neighbour! (6) NEPALI [T]
4 A tiny slave tends sick when love is celebrated by the world (2,10,3) ST VALENTINES DAY*
5 Devious UCLA idol and Spanish leader (8) CAUDILLO*
6 Makeshift robe, possibly for Greta Garbo (6) RAGTAG {RAGTAG+ROBE}*=GRETA GARBO [CD]
7 Oh! It is moment of truth! (4,4) ZERO HOUR {0}{H}
15 Cut melon supply to Black American who is too friendly with whites (5,3) UNCLE TOM*
16 Colt's an example of sporting gun suitable for everyone old! (8) UNGULATE {GUN}{U}{LATE}
17 Married his hairy maiden, has turned into quite a mess! (8) MISHMASH {M}{HIS*}{M}{HAS*}
19 Bold cyber-criminal wanting hot sponsor (6) BACKER {B}{hACKER}
21 Revoke work breaks in modern port (6) NEGATE {NEw}{GATE}
22 Put up with bad run leading to positive change in fortune (6) UPTURN {PUT*}{RUN*}
Reference List
Time = T, Alien = ET, Right = R, Small = S, Charlie = C, 0 = Zero, H = HOUR, Suitable for everyone = U, Married = M, Maiden = M, Bold = B, Hot = H, Work = W
