Rushed to fire rifle (7)
I believe the answer is:
ransack
'rifle' is the definition.
(I know that rifle can be written as ransack)
'rushed to fire' is the wordplay.
'rushed' becomes 'ran'.
'to fire' becomes 'sack' (dismiss someone from their job).
'ran'+'sack'='RANSACK'
(Other definitions for ransack that I've seen before include "Harry" , "Turn upside down in searching" , "Pillage, loot" , "Search (a place) thoroughly" , "Search thoroughly and roughly" .)