Artillery assault? (7)
I believe the answer is:
battery
I believe this is a double definition.
'artillery' is the first definition.
(battery is a kind of artillery)
'assault?' is the second definition.
('battery' can be a synonym of 'assault')
(Other definitions for battery that I've seen before include "Equipment for war" , "Gun emplacement - egg farm" , "Power source; artillery unit" , "Source of charge" , "Personal attack" .)