Cryptic crossword

Across

1 Would a singer have to contradict 21 down? (7-5)

8 Comprehensive reformer could be 5 down (7)

9 Took in position to run workshop (7)

11 The principal part of a march-past (4)

12 Selfish partisan could also be 21 down (10)

14 Inexperienced club have to concede (6)

15 Politicians with first, brief facts and figures (8)

17 Hot-tempered person in legendary war-plane (8)

19 It's quite appropriate to support the Queen (6)

22 Little rascal, over time, had to end obstruction (10)

23 Poet managed to get over slattern (4)

25 Start to get every fruit becoming an abnormal growth (4-3)

26 It's obvious I would enter competition (7)

27 Side is tensed up when it lacked feeling (12)

Down

1 Supplement fish with one line around the Channel Islands (7)

2 Although partly fun, could be a bit strange (4)

3 Have a flair for narrative with a good book (6)

4 About to get different factors in test substances (8)

5 The first principle on a line could be quite simple (10)

6 One poet's upset about a group of drugs (7)

7 Spreading far and wide on the air (12)

10 Left-winger is getting recognition for having to divide things up again (12)

13 Fenced off icon with faith (10)

16 Advertises for annual check-ups, with first engine (8)

18 Want to boost appetite (7)

20 Forecast conditions at the harbour mouth (7)

21 Set on getting under canvas (6)

24 Girl's taking penny from old pick-pockets (4)