British Olympic champion supports time for sport (6)
I believe the answer is:
tennis
'sport' is the definition.
(I know that tennis is a type of ball game)
'british olympic champion supports time' is the wordplay.
'british olympic champion' becomes 'nis' (I can't justify this - if you can you should believe this answer much more).
'supports' means one lot of letters go next to another (bottom letters provide a support for the top ones).
'time' becomes 'ten' (I've seen this before).
'nis' put after 'ten' is 'TENNIS'.
'for' is the link.
Can you help me to learn more?
(Other definitions for tennis that I've seen before include "Net sport" , "Sport with grand slams?" , "Ball sport" , "Racquet-game" , "Racket sport" .)