Something to tickle up the brain cells amid the overindulgence:

1. Coroner's document? Sure thing (4,4) - dead cert

2. Chilly compartment of larynx not very old (6) - icebox

3. Rudimentary state annihilated by Rome (6) - embryo

4. A cry for help brings in top firefighter (8) - asbestos

5. Who in Paris has toxic mix of the ideal and the chivalrous? (8) - quixotic

6. Bloke in forces set landmine off (8,3) - enlisted man

7. No more suckers? That's intolerable (4,5) - last straw

8. Doorbell broken - here one's invited to knock (8) - bordello

9. Time aboard cosy starship is working for scientists (15) - astrophysicists

10. Spooner becomes confused about international killer (8) - poisoner

11. Reciprocated wisdom? (1,5,3,1,5) - a tooth for a tooth

12. Merry band turning up to identify one muppet (10,5) - blithering idiot

2. (vo) ICEBOX

1. Dead cert - nice ones Lex

Bernie

and

9. Astrophysicists (anag "cosy starship is" + t(ime))

3. embryo (anagram of by rome)

Another 2 x

11. a tooth for a tooth

8. bordello (anag. doorbell)

+ 2 = 6 x

4. a sos best --> ASBESTOS

7. last straw

5. quixotic (qui - who in French + toxic - anag.)

6. enlisted man (anag. of set landmines)

+ 4 more =

- directs on the right for both of the last two

Hints: 10 has nothing to do with spoonerisms and 12 is a very British expression

10. poisoner (anag. of spooner containing i)

I think I know what #12 is but I've been enough of a hog.

Thanks Cheryl: please feel free to come back and snag that last one tomorrow if no-one else is biting!

12. blithe/ring i/di/ot (to/id/i backwards)

It helps that, just the other day, I re-watched Harry Potter and the Deathly Hallows.

And the last one bites the dust!

Glad to hear that Harry Potter has helped refine your grasp of English idiom.