Weak charge almost drained (6)
I believe the answer is:
feeble
'weak' is the definition.
(I know that weak can be written as feeble)
'charge almost drained' is the wordplay.
'charge' becomes 'fee' (fee is a kind of charge).
'almost' means to remove the last letter (almost the whole word is kept).
'drained' becomes 'bled' (bleeding is a kind of draining).
'bled' with its final letter taken away is 'ble'.
'fee'+'ble'='FEEBLE'
(Other definitions for feeble that I've seen before include "Weak or ineffective" , "Weak - unconvincing" , "Lacking strength or vigour" , "rather weak" , "lacking resolve" .)