A game and its objective (7)
I believe the answer is:
Here is my best explanation:
'objective' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'a game and its' is the wordplay.
'a game' becomes 'ball' (ball game is a kind of game).
'and' says to put letters next to each other (I've seen this in other clues).
'its' becomes 'net' (I can't explain this - if you can you should believe this answer much more).
'ball' after 'net' is 'NETBALL'.
(Other definitions for netball that I've seen before include "All bent (anag.)", "Team sport", "After this, you get to serve again", "Women's game", "Game for women or girls", "Team game for tall Ben", "Sport whose players wear bibs", "women's game", "Team game/sport" and "Seven-a-side team game -- all bent (anag)".)