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 solve, if not solved by 1 PM.
ACROSS
1 New stem and almost a part of a flower (6) STAMEN {STEM+ANd}*
4 Firm getting a shelter for animals (6) STABLE [DD]
11 Say, Williams finishing off fifth contender untroubled (6) SERENE {SERENa}{c..tEn..r}
12 Daughter with ease, as we hear collected money with people for a leather garment (8) DEERSKIN {D}{(~ease)EE}{RS}{KIN}
13 Courier in trouble, keen to leave a note in place (9) MESSENGER {MESS}{E(-a+n)NGER}
15 Butchery by ex-VP (4) GORE [DD]
16 New small tea stall (4) SEAT {S+TEA}*
17 Say, safety drill conducted by top two cricketers (Ash) at match (5-4) CRASH-TEST {CRi...s}{ASH}{TEST}
21 Squash club collects fee (8) MACERATE {MACE}{RATE}
22 Lost a small plate (6) ASTRAY {A}{S}{TRAY}
24 Deputy's corruption on company lease (10) VICEGERENT {VICE}{GE}{RENT} New word for me
25 Flower offered for God (4) IRIS [DD]
26 Identity card? ID card lost by individual (6) ENTITY idENTITY card
27 Magnificent rehearsal showcases focus (6) CENTRE [T]
DOWN
1 Sleep in small shed, I am told (4-3) SHUT-EYE {S}{HUT}{(~i)EYE}
2 A positive tennis serve, fast (5) APACE {A}{P}{ACE}
3 As per report, agitation at CERN, head dismissed by direction (7) E?S?E?N ()
5 Ostentatious with money, steals regularly (6) TINSEL {TIN}{StEaLs}
6 Forbids to construct plant (5,4) BIRDS FOOT*
7 Controversial agenda tabled by Spain (7) EMOTIVE {MOTIVE}<=>{E}
8 Electrical appliance found at foothill, available at Zepto taken by engineer (6-7) FRIDGE-FREEZER {F}{RIDGE}{FREE}{Z}{ER}
14 Worried people enter vacant tenement after society's communiqué (9) STATEMENT {ATE}{MEN} in {Te...nT} after {S}
18 Upset hero at empty terminal exited entrance (7) STARTLE {STAR}{Te...aL}{Ex...d}
19 Ideas floated in Southern Spain coast (7) SEASIDE {IDEAS}* in {S}{E}
20 Caution in dugout, one taking last wicket (6) CAVEAT {CAVE}{A}{w...eT}
23 Model is not Mark (5) TAINT {T}{'AINT}
Reference List
Money = Rs, Note = N, Small = S, Positive = P, Spain = E, Foot = F, Zepto = Z, Engineer = ER, Society = S, Southern = S, Model = T