Shotgun moved around LA for attack (9)
I believe the answer is:
onslaught
'attack' is the definition.
(an onslaught is an attack)
'shotgun moved around la' is the wordplay.
'moved' is an anagram indicator.
'around' is an insertion indicator.
'shotgun' anagrammed gives 'onsught'.
'onsught' enclosing 'la' is 'ONSLAUGHT'.
'for' acts as a link.
(Other definitions for onslaught that I've seen before include "Heavy attack" , "Fierce attack" , "Barrage" , "Assault" , "Destructive attack" .)