Organisation essential for badminton (5)
I believe the answer is:
admin
'organisation' is the definition.
(short for administration)
'essential for badminton' is the wordplay.
'essential for' indicates a hidden word (I've seen this in other clues).
'ADMIN' can be found hidden inside 'badminton'.
(Other definitions for admin that I've seen before include "Process of running an organisation (abbr)" , "Organisation (colloq.)" , "Business management" , "Business organisation" , "Back-office work (abbr)" .)