Subdue, suppress (5)
I believe the answer is:
quell
I believe this is a double definition.
'subdue' is the first definition.
(I know that quell is a more specific form of subdue)
'suppress' is the second definition.
(quell can mean to suppress or quash)
(Other definitions for quell that I've seen before include "Subdue, suppress" , "Extinguish" , "Put down" , "Suppress completely" .)