Rubbish kisser's naughty coming first (8)
I believe the answer is:
badmouth
'rubbish' is the definition.
(I've seen this before)
'kisser's naughty coming first' is the wordplay.
'kisser' becomes 'mouth' (slang).
'naughty' becomes 'bad' (similar in meaning).
'coming first' means one lot of letters go next to another.
'mouth' after 'bad' is 'BADMOUTH'.
(Other definitions for badmouth that I've seen before include "Halitosis might be a sign of it" , "Run down" , "Throw mud at" , "rubbish" , "Malign" .)