Bread is mine — cheers! (5)
I believe the answer is:
pitta
'bread' is the definition.
(pitta is a type of bread)
'mine cheers' is the wordplay.
'mine' becomes 'pit' (as in a mining pit).
'cheers' becomes 'ta' (both can mean thank you).
'pit'+'ta'='PITTA'
'is' acts as a link.
(Other definitions for pitta that I've seen before include "Bread pocket" , "I might have a kebab in" , "Greek unleavened bread" , "Partially-leavened bread of the Near East" , "Middle Eastern bread" .)