Waistband left in punt (4)
I believe the answer is:
belt
'waistband' is the definition.
(thesaurus)
'left in punt' is the wordplay.
'left' becomes 'l' (common abbreviation).
'in' is an insertion indicator.
'punt' becomes 'bet' (I've seen this in other clues).
'l' inserted within 'bet' is 'BELT'.
(Other definitions for belt that I've seen before include "District" , "Token of judo rank" , "Rush, dash" , "It's worn around the waist" , "Sash" .)