Piece (3)
'piece' is the definition.
(I know that bit is a type of fragment)
This is all the clue.
(Other definitions for bit that I've seen before include "Small fragment" , "Small quantity or piece of metal for a horse" , "Mouthpiece of brindle or tip of drilling tool" , "Sank teeth in" , "Small portion - part of drill" .)
'piece' is the definition.
(I know that piece can be written as part)
This is the entire clue.
(Other definitions for part that I've seen before include "Divide; role" , "Piece, segment" , "Some; break" , "Region" , "goodbye" .)