He's on the staff (3)
I believe the answer is:
rod
I believe this is a double definition.
'he's' is the first definition.
'the staff' is the second definition.
(both can mean a stick or cane)
'on' acts as a link.
(Other definitions for rod that I've seen before include "Angler's cane" , "Spare it and spoil the child, they used to say" , "Measurement" , "Cane used for flogging" , "Flexible stick for 11 Down" .)