Nasty mist with one getting damp (7)
I believe the answer is:
moisten
'damp' is the definition.
(I've seen this before)
'nasty mist with one' is the wordplay.
'nasty' indicates anagramming the letters.
'with' means one lot of letters go next to another.
'mist' put after 'one' is 'onemist'.
'onemist' anagrammed gives 'MOISTEN'.
'getting' acts as a link.
(Other definitions for moisten that I've seen before include "Make damp, say lips with tongue" , "What one's eyes may do!" , "It's on me (anag)" , "Add water - dampen" , "contrary to sixteen down [DEHYDRATE]!" .)