Cryptic crossword No 788

Across

1. Vocalist to improvise around unusual chord - you might catch it live (12,3)
2. Methuselah had to complete a course his boss thought up (7)
3. Naked man possibly relieves 30 older women (7)
4. With lead characters lost, hob must cast spells (5)
5. Stirring cauldron, cut a sinister figure (5,7)
6. One sent down for good over unsuccessful coup, originally (7)
7. Endangered bat's taken to have wings clipped (2,5)
8. A-list brought on board to create comedies (7)
9. Old devil's got a couple of old stars forgetting their lines (2-3-2)
10. Tolkien has him following a ring of gold around (5)
11. Part of a Halloween tradition where a sucker is made to welcome a little rascal (5)
12. Fancy gadget shown in Bond film's teaser? (3,4)
13. Troublemaker finally blowing entrance off Vlad's castle (7)
14. Pole gives attack dog the slip and joins two Italians who escaped long ago (5,7)

Down

1. See 1a
2. Slasher presumably showing vamp with a different origin (7)
3. See 14a
4. Downing Street figure working to upset some players (5)
5. Wickedness to be sent from below (4)
6. Part of window showing star now and then - shut it! (4)
7. Dom's alibi when travelling is fiendish practice (9)
8. Priest cracking hints about contents of early cardinal's tomb (9)
9. Letters regularly dispatched from US to African capital (5)
10. Little attention seekers in hotel with things available at reception (9)
11. Initiating another session about action on pitch (9)
12. Sharp, stinging pain (5)
13. Sign of cross almost knocked European character over (7)
14. A portion of scrambled egg on salmon's picked up and necked (7)
15. Gothic building in which there's a lack of reflection (5)
16. Sorceress wants women to tickle (4)
17. Dress like a folk-tale wolf we've heard about (4)
18. Ultimately obsolete little contraction which we still use occasionally today (3)