Defender of a sport getting the point (9)
I believe the answer is:
apologist
'defender' is the definition.
(I've seen this in another clue)
'a sport getting the point' is the wordplay.
'sport getting' becomes 'polo' (I can't justify this - if you can you should believe this answer much more).
'the point' becomes 'gist' (I've seen this in another clue).
'a'+'polo'+'gist'='APOLOGIST'
'of' is the link.
Can you help me to learn more?
(Other definitions for apologist that I've seen before include "he puts up a defence" , "Champion" , "Advocate" , "One defending the controversial" , "One who defends a policy" .)