Cryptic crossword No 2,778

Across

1. Sporadic occurrences of desirable sex workers circling beach (4,3,6)
2. Issues with European Union lacking resistance against head of Serbia (7)
3. It's simple: I give up (7)
4. Weighty letters between physician and self quoted by Luke? (7)
5. Wieners sometimes made of crushed rats in USA (9)
6. Missing second half, this fool keeled over drunk (5)
7. Turning around, copper encounters drug on board, leading to charges (7)
8. Just some hemp rope rugs (6)
9. Recoil from bird biting hand (6)
10. Reportedly, no public school saved for tomorrow? (7)
11. Doctor Who creature when caught expressed surprise (5)
12. Reveal to reverend where one's partner dwells? (3,4)
13. Moving to Nigeria in spring (9)

Down

1. Reader's picked up by oddly deficient Golf - hardly modern (2,4)
2. Nervy way to access the web (2,4)
3. Times when people let go, as happened in Carthage and Rome (8)
4. Comeuppance for setter eating horse sandwich? (6)
5. Deceitful London institution gets nothing (5)
6. Go where sailors go (4)
7. No doubt lad on vacation religiously uses mobile (9)
8. Denounced and shouted about parasite taking lives for king (10)
9. Sweet, heartless Antarctic? (6)
10. Blast and G-- darn it! (4)
11. Standing stone almost eroded before dusk, essentially (6)
12. Killer song in charts upset Vietnam (6)
13. Mistake found in temperature and air for artificial habitats (8)
14. How footballers might keep ball going round (9)
15. Free love in shed (5)
16. Enjoy wacky Tibetan pop (3,7)