Part gripped (3)
I believe the answer is:
bit
I believe this clue is a double definition.
'part' is the first definition.
(both mean a piece of something)
'gripped' is the second definition.
(biting is a kind of gripping)
(Other definitions for bit that I've seen before include "a curb?" , "Segment" , "The boring-piece of a drill" , "Took effect - fragment" , "Snaffle - small piece" .)