Sport that takes place in a dohyo (4)
I believe the answer is:
sumo
'sport that takes place in a dohyo' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for sumo that I've seen before include "Grappling" , "Style of traditional Japanese wrestling" , "Jap. wrestling" , "Type of Japanese wrestling" , "Japanese wrestling for huge men" .)