Sport for Japanese heavyweights (4)
I believe the answer is:
sumo
'sport for japanese heavyweights' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sumo that I've seen before include "one of the martial arts" , "slappers fighting?" , "Type of Japanese wrestling" , "Japanese wrestling for huge men" , "Grappling" .)