Supporters, say, in outskirts of Leeds (4)
I believe the answer is:
legs
'supporters' is the definition.
'say in outskirts of leeds' is the wordplay.
'say' becomes 'eg' (both can mean for example).
'in' is an insertion indicator.
'outskirts of' means to remove the middle letters (only letters on the outskirts).
'leeds' with its centre taken out is 'ls'.
'eg' inserted inside 'ls' is 'LEGS'.
(Other definitions for legs that I've seen before include "Members" , "Sections of a journey or course" , "Lower limbs" , "Stages of a journey" , "associated with 11 in game" .)