Solution to 25A 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 Former partner not completely inflexible about engaging with sweetheart (2-4) EX-WIFE {FIXEd<=} over {W} and {swEet}
4 Leaders in power saw disheartened youngsters inspiring fashionable visionaries (8) PSYCHICS {Po..r}{Saw}{Yo...rS} over {CHIC}
9 Measure regal London homes (6) GALLON [T]
10 Tough working on his goal after leaving school (8) HOOLIGAN {ON+HIs+GOAL}*
11 So, each goes in lost cause (4,5,5) WILD GOOSE CHASE {SO+EACH+GOES}* [RA]
13 Assign fee (10) COMMISSION [DD]
14 Pair of setters in viral image (4) MEME {ME}{ME}
18 Irreverently, loud sass beginning to provoke worker, largely discontented (10) FLIPPANTLY {F}{LIP}Pr...e}{ANT}{La...lY}
21 What Houdini might have said when denied permission to perform (2,5,3,4) MY HANDS ARE TIED [C&DD]
23 Regretted about magazine's last piece on topless girl published again (8) REISSUED {R{m...nE}{mISS}UED}
25 First knight ringing maiden had to propose (8) N?M?N?T?
DOWN
1 Advantage earned during game especially at the outset (4) EDGE Acrostic
2 With 22 Down, legendary hero shall report around one in the morning (7,4) WILLIAM TELL {WILL}{TELL} over {1 AM}
3 Bright student barging into meals getting drunk (8) FLOODLIT {F{L}OOD}{LIT}
5 Without question, extremely sensuous blouse's a sensation (11) SHOWSTOPPER {HOW} in {Se...oS} and {TOP}{PER}
6 Local icon's clothing material (6) CALICO [T]
8 Therefore, trust in earnest (9) SINCERELY {SINCE}{RELY}
12 Rudely boos the French fragrance that's out of date (11) OBSOLESCENT {BOOS*}{LE}{SCENT}
17 Faith of some oddly following Arab nation mostly lacking resistance (7) BAHAISM {SoMe}<=>{BAHrAIn}
19 Fruitful working together as a set in broadcast (7) TEEMING (~teaming)
20 Quentin's found frequently in concert (6) UNISON {qUeNtInS+fOuNd}
22 See 2 Down
Reference List
With = W, School = S, Loud = L, Student = L, The in French = LE, New = N, Lake = L, Resistance = R