One who no longer works on Scottish island (7)
I believe the answer is:
retiree
'one who no longer works' is the definition.
'on scottish island' is the wordplay.
'on' becomes 're' ('on' can be mean 'with reference to').
'scottish island' becomes 'tiree' (island of the Inner Hebrides).
're'+'tiree'='RETIREE'
(Other definitions for retiree that I've seen before include "Former American worker" , "Person out of work" , "One no longer working" , "One who has ceased to work" , "One having completed work" .)