Annoyed at dirtier bananas (9)
I believe the answer is:
irritated
'annoyed' is the definition.
(I know that annoyed can be written as irritated)
'at dirtier bananas' is the wordplay.
'bananas' indicates anagramming the letters (informal term for mad).
'at'+'dirtier'='atdirtier'
'atdirtier' anagrammed gives 'IRRITATED'.
(Other definitions for irritated that I've seen before include "Annoyed" , "Irked" , "Ratty" , "Vexed" , "rubbed up the wrong way" .)