Midge has unpleasant tang (4)
I believe the answer is:
gnat
'midge' is the definition.
(I've seen this in another clue)
'unpleasant tang' is the wordplay.
'unpleasant' indicates anagramming the letters.
'tang' with letters rearranged gives 'GNAT'.
'has' is the link.
(Other definitions for gnat that I've seen before include "Small (swarming) fly" , "Tiny biter" , "Something that bites" , "Tang (anag.)" , "Small biting flying insect" .)