Agreed on bananas when consuming a fruity drink (9)
I believe the answer is:
orangeade
'fruity drink' is the definition.
(I've seen this before)
'agreed on bananas when consuming a' is the wordplay.
'bananas' indicates anagramming the letters (informal term for mad).
'when consuming' indicates putting letters inside.
'agreed'+'on'='agreedon'
'agreedon' with letters rearranged gives 'orangede'.
'orangede' enclosing 'a' is 'ORANGEADE'.
(Other definitions for orangeade that I've seen before include "Pop" , "Bubbly drink" , "Fruit drink" , "Soft citrus drink" , "Squash" .)