Dismissing, sacking (6)
I believe the answer is:
firing
I believe this is a double definition.
'dismissing' is the first definition.
('fire' can be a synonym of 'dismiss')
'sacking' is the second definition.
(I know that sacking can be written as firing)
(Other definitions for firing that I've seen before include "Dismissing" , "Discharging a gun" , "Shooting; sacking" , "Discharging, sacking" , "Dismissal" .)