Charge drained after electron perimeter weakened (9)

'weakened' is the definition.
(enfeebling is a kind of weakening)

'charge drained after electron perimeter' is the wordplay.
I cannot really see how this works, but
'charge' could be 'fee' (fee is a kind of charge) and 'fee' is located in the answer.
'drained' could be 'bled' (bleeding is a kind of draining) and 'bled' is found within the answer.
'electron' could be 'e' (abbreviation in physics) and 'e' is found in the answer.
A single letter 'n' remains which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?