Round loaf of bread (3)
I believe the answer is:
cob
'round loaf of bread' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for cob that I've seen before include "Swan of Jacobean origin" , "Hazelnut" , "Horse, male swan and loaf of bread" , "Source of bread" , "mixture of clay and straw" .)