Enthusiastic about some badminton (4)
I believe the answer is:
into
'enthusiastic about' is the definition.
(into can mean interested in or enthusiastic about)
'some badminton' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'INTO' is hidden in the letters of 'badminton'.
(Other definitions for into that I've seen before include "Expression of division" , "Keenly interested in" , "Teachers' trade union" , "Keen on, colloquially" , "Taking a lively and active interest in (colloq.)" .)