Fascinated by Badminton shows (4)
I believe the answer is:
into
'fascinated by' is the definition.
(as in being 'into' something)
'badminton shows' is the wordplay.
'shows' says the answer is hidden in the clue.
'INTO' is hidden in the letters of 'badminton'.
(Other definitions for into that I've seen before include "To a position inside" , "digging" , "Showing enthusiasm for" , "Liking" , "Four this twelve is three" .)