Flames in sack (4)
I believe the answer is:
fire
I believe this clue is a double definition.
'flames' is the first definition.
(I've seen this in another clue)
'sack' is the second definition.
(both can mean to dismiss from a job)
'in' acts as a link.
(Other definitions for fire that I've seen before include "Inspire" , "Flames; passion" , "Dismiss; bake in a kiln" , "Trigger" , "... or combustion" .)