Groundnut’s outer layers need to be peeled off — therefore, suffer (7)
I believe the answer is:
undergo
'suffer' is the definition.
(undergoing is a kind of suffering)
'groundnut's outer layers need to be peeled off therefore' is the wordplay.
I cannot really see how this works, but
'be' could be 'go' (going is a kind of being) and 'go' is found within the answer.
The remaining letters 'under' is a valid word which might be clued in a way I don't see.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for undergo that I've seen before include "Endure for guerdon" , "Suffer, experience" , "Endure or be subjected to" , "Experience or live through" , "Endure, experience something" .)