Solution to 14A 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 Stunned by Queen's single (6) NUMBER {NUMB}{ER}
4 Coach and I capably overcome disability (8) HANDICAP [T]
9 Murderer's introduction in suspense film (6) SLAYER {Su...e}{LAYER}
10 They are extremely frugal, singular characters around the banks of Amazon (8) SPARTANS {S}{PART{Am..oN}S}
11 Balanced diet? (4,10) HUNG PARLIAMENT [CD]
13 Old poem featuring exhausted parlour maid dropping off regularly, is excessively stretched (10) OVERSPREAD {O}{VERS{Pa...oR}E}{mAiD}
14 One of five in a litter of horses, discovered (4) ?U?N (Addendum - QUIN eQUINe - See comments)
21 Recorded delivery by agitated deer after tigers dispersed near camp (10,4) REGISTERED POST {DEER*}<=>{TIGERS*} and {POST}
23 Flyers making short trips from half a dozen courtyards on the return journey (3,5) AIR TAXIS {SIX}{ATRIA}<=
24 Absorbing cricket match - openers from Zimbabwe, African champions, belt high above (6) ZODIAC {Zi...e}{ODI}{Af...n}{Ch...s}
25 Scenes from Sci-Fi movie inspired by cheats (8) SETTINGS {S{ET}TINGS}
DOWN
2 Guarantee by Avtaar - not small amount (7) MEASURE {ASsURE}<=>{ME}
3 Stir fresh greens with bits of Indian eggplant (8) ENERGISE {GREENS+In...n+Eg...t}*
5 Name every local heading out, carrying protective gear (11) APPELLATIVE {nA{PELLA}TIVE} Anno pending (Addendum - {ALL}{nATIVE} over {PPE} - See comments)
6 Rear entrance to access Lord's ground (6) DORSAL {Ac..s+LORDS}*
7 Gas and water for the French manor (7) CHATEAU {CHAT}{EAU}
8 Was, perhaps, father nervous about street being evacuated? (4,5) PAST TENSE {PA}{TENSE} over {St..eT}
12 Exposing edges, bird, say, is placing shoots one over the other (3,8) AIR LAYERING {AIR{LAYER}ING}
15 Extremely scratchy mandolin at the start affected musical performance (8) SYMPHONY {Sc...hY}{Ma...n}{PHONY}
19 Do Pranayama on top of church (7) RESPIRE {RE}{SPIRE}
20 Demand by revolutionary group to return soldier in East Africa (6) ASKARI {ASK}{IRA<=}
Reference List
Queen = ER, Singular = S, Old = O, Island = I, Cricket match = ODI, Sci-Fi movie = ET, College = C, Noon = N, Small = S, Protective gear = PPE, Judge = J, On = RE, Saint = S, John = CAN