Its left Bill, the youth leader, with a leg to stand on (6)
I believe the answer is:
legacy
'its left bill the youth leader' is the definition.
I can't judge whether this definition defines the answer.
'a leg to stand on' is the wordplay.
'to stand' becomes 'cy' (I can't explain this - if you can you should believe this answer much more).
'on' is an insertion indicator (as in clothing 'on' a person).
'leg'+'cy'='legcy'
'a' going within 'legcy' is 'LEGACY'.
'with' is the link.
Can you help me to learn more?
(Other definitions for legacy that I've seen before include "A bequest, something left in a will" , "What's left" , "Hand-me-down" , "Something handed down" , "Inheritance" .)