Taste insect that's rolled over (4)
I believe the answer is:
tang
'taste' is the definition.
(I know that tang is a type of taste)
'insect that's rolled over' is the wordplay.
'insect' becomes 'gnat' (gnat is a kind of insect).
'that's rolled over' says the letters should be written in reverse.
'gnat' backwards is 'TANG'.
(Other definitions for tang that I've seen before include "Piquancy - Chinese dynasty" , "The biting flavour of seaweed" , "Savour" , "relish" , "characteristic quality" .)