Cruel king — he dismissed staff (3)
I believe the answer is:
rod
'staff' is the definition.
(both can mean a stick or cane)
'cruel king he dismissed' is the wordplay.
'cruel king' becomes 'herod' (I've seen this before).
'dismissed' indicates named letters should be taken away.
'herod' with 'he' removed is 'ROD'.
(Other definitions for rod that I've seen before include "Imperial measure" , "Sceptre" , "Cane used for flogging" , "something fisherman brings home" , "- - , pole or perch" .)