Bananas, biscuits and bangers (8)
I believe the answer is:
crackers
I believe this is a triple definition!
'bananas' is the first definition.
(both can informally mean mad)
'biscuits' is the second definition.
(I've seen this before)
'and' is a link.
'bangers' is the third definition.
(both can mean fireworks)
(Other definitions for crackers that I've seen before include "Mad - biscuits" , "Mad - fireworks" , "Pulled at parties!" , "Round the bend" , "Christmas items" .)