Cryptic crossword

ACROSS

1. They were sometimes held to be more illuminating (12) 7. It dies at the end of December (5) 8. It’s straightforward and on the level (5) 9. A tower of strength (3) 10. Most foolish, however? (9) 11. Roadside place for those low in spirit? (6) 12. The comfort of the man taking over? (6) 15. The way to cure behaviour? (9) 17. A number of vital importance (3) 18. Heart-broken world (5) 19. An odd type of route (5) 21. He isn’t a good forecaster (7,2,3)

DOWN

1. Assemble and call for a lady (4,8) 2. Strike up (3) 3. Master’s current form (6) 4. In a hurry to make me paint it (9) 5. Colour uniformly used (5) 6. Intrusion which may spoil the reception (12) 7. Agree to be enthusiastic (5) 10. His plight might possibly warn sailors (9) 13. Silly Annie is upset (5) 14. Suit to change into? (6) 16. The fault of some terrorists (5) 20. As well as the first fifteen letters (3)