The raw bananas: I try a dish, but ... (8,4)
I believe the answer is:
birthday suit
'the raw' is the definition.
('birthday suit' can be a synonym of 'raw')
'bananas i try a dish but' is the wordplay.
'bananas' indicates anagramming the letters (informal term for mad).
'i'+'try'+'a'+'dish'+'but'='itryadishbut'
'itryadishbut' with letters rearranged gives 'BIRTHDAY SUIT'.
(Other definitions for birthday suit that I've seen before include "State of being unclothed" , "Invisible attire?" , "State of total nakedness" , "Invisible outfit?" , "Invisible threads?" .)