Boring rhubarb — 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 don't understand how they can define each other.
'boring rhubarb' is the wordplay.
'boring' becomes 'dry' (dry can mean dull or boring).
'rhubarb' becomes 'rot' (both can mean nonsense or false information).
'dry'+'rot'='DRY-ROT'
Can you help me to learn more?
(Other definitions for dry rot that I've seen before include "problem with deal?" , "it may make one's beam disappear" , "Timber disease" , "Degeneration" , "problem with truss?" .)