Experience insufficient energy? (7)
I believe the answer is:
undergo
'experience' is the definition.
(I know that experience is a more specific form of the action undergo)
'insufficient energy?' is the wordplay.
'insufficient' becomes 'under' (I am not sure about this - if you are sure you should believe this answer much more).
'energy?' becomes 'go' (I've seen this in other clues).
'under'+'go'='UNDERGO'
Can you help me to learn more?
(Other definitions for undergo that I've seen before include "Guerdon (anag.)" , "experience needed" , "Experience, be subjected to" , "Suffer, experience" , "Withstand" .)