Old lady eating one's bread (4)
I believe the answer is:
naan
'bread' is the definition.
(I know that naan is a type of bread)
'old lady eating one's' is the wordplay.
'old lady' becomes 'nan' (British slang for grandmother).
'eating' means one lot of letters goes inside another.
'one' becomes 'a' (a thing is one thing).
'nan' going around 'a' is 'NAAN'.
(Other definitions for naan that I've seen before include "Indian food" , "foreign food" , "Indian leavened bread" , "Indian flat bread" , "Indian type of bread" .)