Serve badly in the game (7)
I believe the answer is:
netball
'serve badly' is the definition.
The definition and answer can be both acts as well as being singular nouns.
Maybe there's a link between them I don't understand?
'in the game' is the wordplay.
'in the' becomes 'net' (I can't justify this - if you can you should give a lot more credence to this answer).
'game' becomes 'ball game' (ball game is a kind of game).
'net'+'ball'='NETBALL'
Can you help me to learn more?
(Other definitions for netball that I've seen before include "Sport whose players wear bibs" , "activity no longer associated solely with girls" , "Team game/sport" , "Game for women or girls" , "Team game, played mainly by women" .)