Said it's part bread (4)
I believe the answer is:
roll
'bread' is the definition.
(I know that roll is a type of bread)
'said it's part' is the wordplay.
'said' indicates a 'sounds like' (homophone) clue.
'it's part' becomes 'role' (eg a theatrical role).
'role' sounds like 'ROLL'.
(Other definitions for roll that I've seen before include "one filled at lunchtime, perhaps" , "Eg, bap" , "Cylinder (of paper etc)" , "start recording film" , "Official list; cylinder" .)