Got off line in island (4)
I believe the answer is:
alit
'got off' is the definition.
('alight' can mean to get off a vehicle)
'line in island' is the wordplay.
'line' becomes 'l' (used when specifying particular lines from a poem).
'in' indicates putting letters inside.
'island' becomes 'ait' (term for a small island).
'l' going inside 'ait' is 'ALIT'.
(Other definitions for alit that I've seen before include "Settled" , "got off" , "Came down to earth" , "Landed" , "Climbed down from" .)