Plug, stopper (4)
I believe the answer is:
bung
I believe this is a double definition.
'plug' is the first definition.
(bung is a kind of plug)
'stopper' is the second definition.
(bung is a kind of stopper)
(Other definitions for bung that I've seen before include "Bribe (slang)" , "Cask stopper" , "Plug for a hole in a barrel or boat" , "illegal incentive" , "Bribe; throw" .)