Down-sell for sport (4)
I believe the answer is:
golf
'for sport' is the definition.
(golf is a kind of sport)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for golf that I've seen before include "Eighteen-hole game" , "Outdoor game" , "Something played" , "Game with tees" , "Leonhard -, Swiss mathematician/physicist" .)