Solution to 3D 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
1 Assign setter's place at end of table (6) IMPUTE {I'M}{PUT}{t..lE}
4 Venerable members of crusade meet secretly in retreat (8) ESTEEMED [T<=]
10 Healthy boxer is against bananas (9) ALIMENTAL {ALI}{MENTAL}
11 Worm's stroke of luck (5) FLUKE [DD]
12 Crowd laments over losing last of matches and rubber (7) MASSEUR {MASS}{RUEs<=}
13 Team's turn to play in pub and sing drunkenly (7) INNINGS {INN}{SING*}
14 In America, son of immigrants rejected? That's wrong (5) NISEI {IE}{SIN}<=
15 Takes possession of international banks, having power (8) IMPOUNDS {I}{M{P}OUNDS}
18 One Malayali winning preliminary race, cycling all around One Malayali leaving America wins preliminary race, cycling all around(2,3,3) IN THE AIR {1}{NaIR} over {(+t)THEA(-t)} Clue being edited by KrisKross
20 Work in short-sleeved shirt and lightweight hat (5) TOPEE {T{OP}EE}
23 Muscles love running free! (7) ABSOLVE {ABS}{LOVE*}
25 Cooked nan - neat dish perhaps (7) ANTENNA*
26 Rebellious soldiers welcomed by the old adversary (5) ENEMY {Y{MEN}E}<=
27 Creature often contaminating kitchens, running over appliances, creating havoc primarily (9) COCKROACH Acrostic &lit
DOWN
3 Cutting piece of cloth, start to wrap present afterwards (9) T?E?E?I?H ()
5 Egotism of man going through elaborate profile in Outook (4-10) SELF-IMPORTANCE {M} through {PROFILE*} in {STANCE}
6 Delicate fellow bathed in Northbound river (5) ELFIN {NI{F}LE<=}
7 Evil demon controlling ancient city felt sad (7) MOURNED {MO{UR}NED*}
8 Elegant English ship stops, having no water (6) DRESSY {DR{E}{SS}Y}
9 How to create acute pain, worry about something trivial? (5,2,1,6) STORM IN A TEACUP {ACUTE+PAIN}* [RA]
16 Fan turned out to be ignorant (9) UNTUTORED*
17 Tech giant announced "Warning!" symbol (8) METAPHOR {META}{(~fore)PHOR}
19 Developing space agency mostly with American money (7) NASCENT {NASa}{CENT}
21 Aim to cut long ornament (7) PENDANT {P{END}ANT}
22 Beware! Machinery has rotating device (6) CAMERA [T<=]
24 Expression of amusement describing unknown American firm (5) LOYAL {LOL} over {Y}{A}
Reference List
Muscles = ABS, The old = YE, Right = R, Man = M, Fellow = F, Ancient city = UR, English = E, Ship = SS, Unknown = Y, American = A