Gauff clubs ball repeatedly (4)
I believe the answer is:
coco
'gauff' is the definition.
I can't judge whether this definition defines the answer.
'clubs ball repeatedly' is the wordplay.
'clubs' becomes 'c' (abbreviation used in card games such as bridge).
'ball' becomes 'o' (O looks like a ball).
'repeatedly' shows that letters should be duplicated.
'c'+'o'='co'
'co' doubled is 'COCO'.
Can you help me to learn more?
(Other definitions for coco that I've seen before include "French fashion designer, who branched into perfume etc" , "Gabrielle Bonheur Chanel" , "'... the Clown, ... Chanel (4)'" , "address for Chanel" , "Famous clown" .)