Solution to 4D 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 solve, if not solved by 1 PM.
ACROSS
6 Set up home on land (7) INSTATE {IN}{STATE}
7 Setback on tour, second on second test (7) RELAPSE {RE}{LAP}{S}{tEst}
9 Receiver on training? Yes, internal (5) PAYEE {P{AYE}E}
10 English stall fight (9) ENCOUNTER {EN}{COUNTER}
11 Stew! Laughs raucously after taking a round (7) GOULASH {G{O}ULASH*}
15 Property I have on headland is on use (13) EFFECTIVENESS {EFFECT}{IVE}{NESS}
20 New series? At last you dug into a copy (7) REISSUE {REISS{yoU}E*}
23 Heartless hatred & hard? No, it's a show (9) SPLENDOUR {SPLeEN}{DOUR}
24 Letters from Putin trolling presentation (5) INTRO [T]
DOWN
1 Pale like gutted hubby (4) ASHY {AS}{HubbY}
2 Arrived with artist and snapper, say (6) CAMERA {CAME}{RA}
3 Type of lens used by predecessor (9) TELEPHOTO [DBE]
4 Replacing one by one, suggestion that it's a mirage (8) ?L?U?I?N (Addendum - ILLUSION (-a+i)ILLUSION - See comments)
5 Hope oats is cooked well and becomes an ideal example (10) APOTHEOSIS*
6 Challenge imperfect undergraduate on numbers (6) IMPUGN {IMP}{UG}{N}
7 Energetic orchestra? Cynical nearly (4) RACY [T]
8 Mistake with commission (6) ERRAND {ERR}{AND}
12 Angry unfair mail, that's strange (10) UNFAMILIAR*
14 Always immature to pine, say (9) EVERGREEN {EVER}{GREEN}
16 Inside president angled with a knot (8) ENTANGLE [T]
17 Cats runs around having drink and misbehaves (4,2) ACTS UP {ACT*}{SUP} Should have been CAT and not CATS
18 Request individual? Go away (6) BEGONE {BEG}{ONE}
21 I primarily contracted lice infection leading to cold spike (6) ICICLE {I}{Co...d}{LICE*}
22 Ball placed in carpet is in wide ditch (4) MOAT {M{O}AT}
25 Record a form of dance (European) (4) TAPE {TAP}{E}
Reference List
Home = IN, Tour = LAP, Second = S, Training = PE, English = EN, Company = CO, English = E, Artist = RA, Undergraduate = UG, Numbers = N, European = E