Thanks for your help everyone.
If 3d is OVERCLOUD then I can't understand 12a. The clue for 12a is:
Georgia meets bad bloke, murderer (8).
I thought this was GARROTER but if OVERCLOUD is right, then the answer must be GAROTTER. This fits better (GA=Georgia, ROTTER=bad bloke) but according to my dictionary this is an incorrect spelling.
Can GARROTER be spelt GAROTTER?