Cryptic crossword No 4,117

Across

1. Choose to retire during decadent celebration (5)
2. A bishop hit 18's uncle (5)
3. 18's son at the start of the working week (5)
4. Smallest man in Mali, perhaps? (7)
5. Looks good, Nick and Bob (7)
6. Biblical character's destiny (3)
7. Support for art student after decrease (5)
8. Detailed discourse follows clobbering of Abel (9)
9. Pick up knight after king (5)
10. Doctor Who's sad remnants (7)
11. News story? Clear it with the editor (7)
12. Stage I: Reading, writing and arithmetic can lead to admin role (9)
13. Man with former currency accepted in Switzerland? The opposite is standard (9)
14. Cheap drink brought by server without ice, initially (5)
15. Three-legged race? (9)

Down

1. Cut when half-cut (4)
2. Let explosion of Pearl Harbor risk endless vengeance? (8)
3. Harmony of sound in Paris, for example (10)
4. Finally repairing poorly sister's breathing equipment (5)
5. Celebration after girl died inside nuclear complex (8)
6. Ministry's remix of "Green" on MTV (10)
7. It's charged at the first signs of mother or son returning (6)
8. Even the ghost train is here (4)
9. Results of depleted electron discharges (4)
10. Eats a crumpet containing bone (6)
11. No longer in the dark about amount of 31 (5)
12. Learning to fall in time, like Mahler's 4th (8)
13. Dazzles Nan with chest exercises (8)
14. Scared of a loud rifle (6)
15. Villain's on the back foot (4)
16. Done quietly, let out after vehicle's return journey (6)
17. Name of knight besieging city (4)
18. What happens after John performs (4)