Bangers, nuts and bananas not all there (8)
I believe the answer is:
crackers
I believe this clue is a quadruple definition!!
'bangers' is the first definition.
(both can mean fireworks)
'nuts' is the second definition.
(both can informally mean mad)
'and' is a link.
'bananas' is the third definition.
(both can informally mean mad)
'not all there' is the fourth definition.
(both can mean insane)
(Other definitions for crackers that I've seen before include "Mad - fireworks" , "and some others touched" , "Crazy - (American) biscuits" , "Nutty - biscuits" , "Round the bend" .)