I've just got two left (and possibly 2D as my answer is prob. wrong):-
1D Dance, say, a lively dance to lose weight (7)
---R-E-
6A Highly acidic sulphur rings (6), which with the addition of one letter which I won't give away yet, makes a new 7-letter word which has E as the penultimate letter
I assume it's a word for 'highly acidic' + S for sulphur, meaning rings, but as I managed to learn zero science at school, my brain seizes up at the mention of anything remotely scientific.
2D Wasting life and heading for emergency gunfire (8)
---I-A-E
I have a word meaning 'wasting' but can't parse the rest at all, so I assume it's wrong.
Also, I can't totally parse:
3D Part of car requiring change at the back, covering miles (8)
I have part of an engine as the answer. If miles = MS, and back is, as someone here said, the back of a boat (3 letters), that still leaves 3 letters. The first 2 could be 'part of car' but that's the definition and that still leaves 1 letter. How does it work?
Any help much appreciated.