Worn out friend — that's a no-win situation (9)
I believe the answer is:
stalemate
'a no-win situation' is the definition.
(situation in chess in which neither player can win)
'worn out friend' is the wordplay.
'worn out' becomes 'stale' (stale can mean worn out or hackneyed).
'friend' becomes 'mate' (mate is a kind of friend).
'stale'+'mate'='STALEMATE'
'that's' acts as a link.
(Other definitions for stalemate that I've seen before include "Deadlock, impasse" , "Inglorious deadlock" , "a position on board" , "Situation offering no way forward" , "Indecisive chess ending" .)