Cryptic crossword No 3,973

Across

1. Using heel, own goals made stranger cry (6)
2. Company overwhelmed by work in the future (2,4)
3. City in the Trojan war kept heads of pointed harpoons as keepsake (6)
4. Assassins possibly strangled one leader of Chicago police (8)
5. See writer's inside luxurious car (4)
6. Crook howls after training exercise (10)
7. One spotted on thin ice? (7,4)
8. Rules of The London Tube? (10)
9. Initially knee-deep in tea brew extract (4)
10. Limp fall to Spooner's watery mixture? (5,3)
11. Tar over street with right turns and stops (6)
12. Worked as a dealer, readied all but beginner in poker (6)
13. Aloof representative on vacation quiet once more (6)

Down

1. Drafted missing content of haiku to read when travelling (8)
2. Those after the girls in school tests across year (6)
3. Made situation worse for oneself when cycling in tears (8)
4. Oddly sick of jams (prune) in European capital (6)
5. Cutting heart of pig out of corpses for essentially fat workers (6)
6. Leave bottle's cap enclosing bottles (6)
7. Rough nose of sailing boat (6)
8. Topless troublemakers - boobs! (6)
9. Channel running for audience (6)
10. Old couple finds advantageous ambiguity in agreement (8)
11. Far from close, currently at this place, short nobleman housed knight (7,4)
12. One down for the count? (8)
13. Butcher lost marlin's head for fisherman (6)