Japanese wrestling (4)
'japanese wrestling' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for sumo that I've seen before include "one of the martial arts" , "Type of Japanese wrestling" , "Japanese wrestling for huge men" , "Japanese form of wrestling" , "Style of traditional Japanese wrestling" .)
(Other definitions for jujitsu that I've seen before include "Japanese method of unarmed self-defence" , "Japanese unarmed combat" , "Samurai's unarmed self-defence martial art" , "Samurai self-defence" , "Jap. unarmed combat" .)