Shut forcefully (4)
I believe the answer is:
slam
'shut forcefully' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for slam that I've seen before include "Criticise - attack" , "Shut (door) with force" , "A grand one is 13 tricks" , "Shut hard" , "Shut (a door) noisily" .)