Bung, plug (7)
I believe the answer is:
stopper
I believe this is a double definition.
'bung' is the first definition.
(I know that Stopper is a bung)
'plug' is the second definition.
(I know that stopper is a kind of plug)
(Other definitions for stopper that I've seen before include "One who checks" , "Cork - goalkeeper?" , "Maybe cork" , "Plug for a bottle" , "Plug - cork" .)