Cryptic crossword No 4,123

Across

1. Trains school assembly to omit hymns at first (5)
2. Wise men abbreviated spelling (4)
3. Difficulty accommodating cargo, perhaps (4)
4. Providing sponsorship, finish up in debt (8)
5. Force European to accept introductions of immigrant children (6)
6. Sally about to get arty, we hear (6)
7. Sickly lambs she leads to abbatoir (8)
8. Sweeping at home, disorder let in a vagrant (11)
9. Philanthropy is found in strange surroundings, key to be ahead (8)
10. Fabricated boat not launched, regret follows (6)
11. Amazingly cheerful to be consuming fruit (6)
12. Examine damaged cars here (8)
13. Bargain to get pins back (4)
14. Heartless boss becomes saucier? (4)
15. Box like a rogue? (5)

Down

1. Birthday boy, maybe, suffers diatribe from VIP? (9)
2. QI? - MI5? (7-12)
3. Cry of disapproval engulfs unknown Welshman? (4)
4. Suspend article in mercury (4)
5. Lily's sapphire must be reset (12)
6. NBC leak disseminated slander (7)
7. See 1d
8. Ending it all, reportedly, it's you I see inside? (7)
9. Dance about the Spanish (4)
10. Open a container? (4)
11. Be hot and bothered, leaves, getting into S & M (5)
12. Quietly betting on (7)
13. Possession which freight carrier might need to be delivered (9)