Fill ward (6)
I believe the answer is:
charge
This clue is a double definition.
'fill' is the first definition.
(charging is a kind of filling)
'ward' is the second definition.
(thesaurus)
(Other definitions for charge that I've seen before include "Set price or mount onslaught" , "Formally accuse (someone)" , "Amount to pay - attack" , "Attack - cost" , "Rush forward - cost" .)