Unpleasantly moist (4)
I believe the answer is:
dank
'unpleasantly moist' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for dank that I've seen before include "(Of atmosphere) wet and unpleasant" , "Chilly and clammy" , "Unpleasantly cool and damp" , "Unpleasantly cold and humid" , "Cold and moist" .)