Mist one amazingly wet (7)
I believe the answer is:
moisten
'wet' is the definition.
(moistening is a kind of wetting)
'mist one amazingly' is the wordplay.
'amazingly' indicates an anagram.
'mist'+'one'='mistone'
'mistone' with letters rearranged gives 'MOISTEN'.
(Other definitions for moisten that I've seen before include "Add water - dampen" , "It's on me (anag)" , "contrary to sixteen down [DEHYDRATE]!" , "What one's eyes may do!" , "Make damp or slightly wet" .)