Cryptic crossword No 3,999

Across

1. Save muntjacs possibly around 54 (7)
2. Salmon primarily return to sea in groups (7)
3. Home nations sell EU broken instruments (8)
4. Spooner's young male android is a disreputable character (3,3)
5. Balls alternatively utter nonsense! (4)
6. She's a key operative in black and white (5,6)
7. Jezebel's third character leaving Cornish town in expiation (7)
8. Short of arms damaged vessels secure protection (10)
9. Test electric current for transport (4)
10. Gullies stretch northeast crookedly without end in sight (8)
11. Starters of Italian gnocchi with lasagne ordered for Scot (10)
12. Still rubbish I found in charity shop originally returned (6)
13. Backup on tape produced when server's corrupted last part of file (7)

Down

1. Sloppiness is oddly nice appearing in skimpy robe (10)
2. Marsupial not at place that supports life? (4)
3. Labrador dog nearly goes across French river (8)
4. Eight Italian staff in storage facility (7)
5. He for one is not wanting to move and chat up North (5,3)
6. Plant from Colorado planted back in California (4)
7. Market unfinished church property in Scottish town (7)
8. Swings by golfer Michelle left divots unfilled (6)
9. Part of job let Hermione prattle on (7)
10. Cost incurred by former VP reported (7)
11. Pass through bushes scratching top of head (6)
12. Initially William Hill announced takings cut gaining nothing at all (10)
13. Key departments losing guaranteed future credit ultimately disastrous for banks (11)