Starter of dates or try bananas -- this can make fruit crumble (3,3)
I believe the answer is:
dry rot
'this can make fruit crumble' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'starter of dates or try bananas' is the wordplay.
'starter of' indicates taking the first letters.
'bananas' indicates an anagram (informal term for mad).
The first letter of 'dates' is 'd'.
'or'+'try'='ortry'
'ortry' is an anagram of 'ryrot'.
'd'+'ryrot'='DRY-ROT'
Can you help me to learn more?
(Other definitions for dry rot that I've seen before include "Usual, customary" , "Decay of timber caused by fungus" , "Fungus attacking wood" , "Disease of wood not well ventilated" , "Degeneration" .)