Outcast from old French island (5)
I believe the answer is:
exile
'outcast' is the definition.
(I've seen this before)
'old french island' is the wordplay.
'old' becomes 'ex' (prefix meaning former or onetime).
'french island' becomes 'ile' ('island' in French).
'ex'+'ile'='EXILE'
'from' is the link.
(Other definitions for exile that I've seen before include "Ban to abroad" , "Bar (someone) from their native country" , "Ousted person" , "Person forced to live abroad" , "Expel from home or country" .)