Fire in container (4)
I believe the answer is:
sack
I believe this clue is a double definition.
'fire' is the first definition.
(dismiss someone from their job)
'container' is the second definition.
(I know that sack is a type of container)
'in' is the link.
(Other definitions for sack that I've seen before include "Fire the old drink?" , "Big, coarse bag" , "Flour or grain bag" , "Dismiss (from a job)" , "Devastate" .)