Cryptic crossword No 2,171

Across

1. Hanging pawns stopping attack (6)
2. Where to find drones? High Barnet (7)
3. Head of state takes drug for dinner (6)
4. Start after getting this clue (not long) (3)
5. Look children, it's wet in Scotland! (4)
6. Cigogne losing heart after Guava finally becomes number one (3)
7. Joint from Dasher, cooked (6)
8. Not as many shorn sheep (3)
9. See 21
10. Cry of resignation in French castle I've ruined (4,2,3)
11. Exhaust from traffic, perhaps, envelopes street development (3,6)
12. In song before the season? Relax! (3)
13. Christmas crossword? Hard - I'm not certain to bother (6)
14. In first place, Fez, perhaps, might use this to trick everyone! (3,3)
15. A number unknown? (3)
16. Disregard bottom on the counter (4)
17. In essence, thepoisonedgift has an issue (3)
18. Liberal Democrats' comeback bears fruit (6)
19. Competition in which Coot regularly appears with new experiment (7)
20. Unease as one's trousers fall in New York? (6)

Down

1. Every now and then fill up Sheikh's case with money (5)
2. Spears famed for funky no. 1s? (9)
3. Retiring journalist gets a reprimand for column (6)
4. Small amounts of semen let out (8)
5. Share the win when seeing what Blah and Polymath have in common in composition - primarily, verbal expressiveness (5)
6. Endless corruption leads Conservatives to landslides (9)
7. Wrinkly nana in Crete? (11)
8. Baldur disheartened by new intake - Gobbo's latest to find success in their career, say (5,4)
9. Boring long range forecast: essentially hot Down Under (9)
10. Keep them or piss me off! (8)
11. Block my site after it's corrupted (6)
12. Tip from Henri: start to acquire touch and style (5)
13. A win once more (5)