Midge has unfamiliar tang (4)
I believe the answer is:
gnat
'midge' is the definition.
(thesaurus)
'unfamiliar tang' is the wordplay.
'unfamiliar' indicates anagramming the letters.
'tang' anagrammed gives 'GNAT'.
'has' is the link.
(Other definitions for gnat that I've seen before include "Any of various small biting flies" , "Tang of a biting fly" , "Tiny biting insect" , "Biting pest" , "Small biting flying insect" .)