Charge gunners a lot! (3)
I believe the answer is:
ram
'charge' is the definition.
(I've seen this in other clues)
'gunners a lot' is the wordplay.
'gunners' becomes 'ra' (Royal Artillery).
'a lot' becomes 'm' ().
'ra'+'m'='RAM'
(Other definitions for ram that I've seen before include "Aggressive sheep?" , "what comes after fish" , "force" , "Tamp" , "Male sheep - bash into it" .)