Insect of biting nature (4)
I believe the answer is:
gnat
'insect' is the definition.
(gnat is a kind of insect)
'of biting nature' is the wordplay.
'of' says the answer is hidden in the clue.
'GNAT' is hidden in the letters of 'biting nature'.
(Other definitions for gnat that I've seen before include "Small biting flying insect" , "small irritant" , "Biting pest" , "Small biter" , "Small bloodsucker" .)