Solution to 8A 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 Difference in attitudes breaking up ageing parent and son essentially (10,3) GENERATION GAP {AGEING+PARENT+sOn}* &lit
8 Forces controlled by Maoist in underground revolution (5) U?I?S ()
9 Men reviewed problem with main knob controlling church pipes (5,4) ORGAN STOP {OR}{SNAG<=}{TOP}
11 & 18 Detailed narrative in breezy weather report? (4-2-4,7) BLOW-BY-BLOW ACCOUNT {C&DD]
12 Hotel just needs strong locks (4) HAIR {H}{fAIR}
14 Characters in terrible unrest around America (7) NATURES {N{A}TURES*}
16 Rebellious writer in European country acting out awkwardly (7) INEPTLY {I{PEN<=}TaLY}
17 Worrying about daughter hooking up on the internet (1-6) E-DATING {E{D}ATING}
19
Granitic rock is found in lawn (7)
GREISEN {GRE{IS}EN}
21
Every beauty's topless (4)
EACH pEACH
22 Swindle by phoney tourism company (10) CONSORTIUM {CON}{TOURISM*}
25 More courageous with money belt (9) DOUGHTIER {DOUGH}{TIER}
26 Dog picking up right scent (5) TRAIL {T{R}AIL}
27 Gain an advantage over some charlatan easily (5,1,5,2) STEAL A MARCH ON*
DOWN
2 Remove part of text from it due to blunders (4,3) EDIT OUT* &lit
3 Order of demolition finally liberates Cold War capital (4,6) EAST BERLIN {d...oN+LIBERATES}*
4 America, Britain hosting gathering about nuclear weapon (1-4) A-BOMB {A}{MOB<=}{B}
5 Popular girl arguing is getting under one's skin (9) INGROWING {IN}{G}{ROWING}
6 Number series, new for student (4) NINE (-l+n)NINE
7 Seduce a model with finesse, overcoming resistance (7) ATTRACT {A}{T}{T{R}ACT}
8 Myth or otherwise, a blunder to consume dope (5,6) URBAN LEGEND {A+BLUNDER}* over {GEN}
10 Socialite raised drink, cuddling pretentious maiden in a retreat (5,6) PARTY ANIMAL {LAP<=} over {ARTY}{M+IN+A<=}
13 Erotic item shaped like a heavenly body (10) METEORITIC*
15 Unmarried Italian woman and character cavorting on air (9) SIGNORINA {SIGN}{ON+AIR}*
18 See 11 Across
20 Largely formal event featuring
a Greek dish (7)
STIFADO {STIF
f}{A}{DO}
23 Extremely
scar
y broadcast about
Middle Eastern country (5)
SYRIA {S
carY}{AIR<=}
24 Hunte
r heartlessly traps
bird (4)
RHEA [T]

Reference List
Men = OR, Hotel = H, Strong = F, America = A, Acting = A, Daughter = D, Right = R, Britian = B, Girl = G, New = N, Student = L, Model = T, Resistance = R. Dope = GEN, Maiden = M, Event = DO