Defeated, having dined on a piece of bread (6)
I believe the answer is:
beaten
'defeated' is the definition.
(similar in meaning)
'dined on a piece of bread' is the wordplay.
'dined' becomes 'eaten' (having had a meal).
'on' is a charade indicator (letters next to each other).
'a piece of' suggests taking the first letters.
The initial letter of 'bread' is 'b'.
'eaten' put after 'b' is 'BEATEN'.
'having' acts as a link.
(Other definitions for beaten that I've seen before include "Baffled" , "Defeated - whipped" , "Vanquished" , "Failed to win - punished" , "Worsted" .)