Join the staff (5)
I believe the answer is:
stick
This clue is a double definition.
'join' is the first definition.
(I know that fasten is a is a more specific form of the action of stick)
'staff' is the second definition.
(I've seen this before)
'the' acts as a link.
(Other definitions for stick that I've seen before include "Join firm" , "Staff - criticism" , "Adhere; baton" , "Rod" , "Switch < put up" .)