Solving time, 19 mins. The usual pleasing puzzle.
* = anagram < = reversed
ACROSS
6 Margaret (D)RABBLE D = daughter
8 N A (S)T IVES
9 ST RAPPER
11 NA (RK) ED dean<
12 DUD E
13 STAY-AT-HOME (May hate to s = beginning to stir)* &lit
15 NEMESIA (meanies)*
17 AD VERSE Horace wrote in the BC era
20 SERPE(N)TINE Lake in Hyde Park, London (pine trees)*
22 DO SH
23 G (A RR) ET
24 L OP TROON Troon = golf course in Scotland
26 STA (P)LER
27 CAST(L)E definition = keep
DOWN
1 PRES (1 D) ENTS one old pre-1971 penny (d)
2 SLOP(e)
3 STANDARD CELL
4 OVERSHOE Cryptic definition pump = shoe
5 battlE STEEM meets<
7 BOREDOM (me brood)*
8 NORMAN cf normal
10 PASSIONATELY (Any apostle is)*
14 EVEN-HANDED definition: just (have end end)*
16 EMP(t)Y REAL
18 R (OOT) OUT too<
19 NIP PER (rep)< (pin)<
21 thE LAPSE
25 TEAL alternate letters in ‘the tail’