Playing Quidditch one needs such courage (5)
I believe the answer is:
balls
'courage' is the definition.
(thesaurus)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for balls that I've seen before include "See 7" , "Formal dances" , "nonsense" , "deliveries" , "Rubbish" .)