Left home, absorbed by island's horizon (7)
I believe the answer is:
skyline
'horizon' is the definition.
('skyline' can be a synonym of 'horizon')
'left home absorbed by island's' is the wordplay.
'left' becomes 'l' (common abbreviation).
'home' becomes 'in' ('he's home' can mean 'he's in').
'absorbed by' indicates putting letters inside.
'island' becomes 'skye' (I've seen this before**).
'l'+'in'='lin'
'lin' placed into 'skye' is 'SKYLINE'.
(Other definitions for skyline that I've seen before include "Visible horizon" , "Silhouette or outline of buildings" , "Horizon; like NY's (anag.)" , "Built-up horizon" , "Outline of hills or buildings against firmament" .)