Fruit if gone off could make Beryl groan (10)
I believe the answer is:
loganberry
'fruit' is the definition.
(loganberry is a kind of fruit)
'make beryl groan' is the wordplay.
'make' indicates an anagram.
'beryl'+'groan'='berylgroan'
'berylgroan' anagrammed gives 'LOGANBERRY'.
'if gone off could' is the link.
This may not be right. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for loganberry that I've seen before include "Edible soft red fruit" , "Hybrid fruit plant" .)