Old school friend's tie (9)
I believe the answer is:
stalemate
'tie' is the definition.
(tie in chess)
'old school friend's' is the wordplay.
'old' becomes 'stale' (similar in meaning).
'school friend' becomes 'mate' (I can't explain this - if you can you should give a lot more credence to this answer).
'stale'+'mate'='STALEMATE'
Can you help me to learn more?
(Other definitions for stalemate that I've seen before include "Unresolvable position" , "Deadlocked position" , "Deadlock, impasse" , "Chess game deadlock" , "situation without a winner" .)