Cry of pain after charges surge (6)
I believe the answer is:
billow
'surge' is the definition.
(synonyms)
'cry of pain after charges' is the wordplay.
'cry of pain' becomes 'ow' (exclamation of pain).
'after' says to put letters next to each other.
'charges' becomes 'bill' (I can't justify this - if you can you should believe this answer much more).
'ow' put after 'bill' is 'BILLOW'.
Can you help me to learn more?
(Other definitions for billow that I've seen before include "A great wave or swell" , "Surge" , "Swell out (as a sail)" , "Wave; upward flow" , "Swell out in the wind" .)