Island's central road (6)
I believe the answer is:
midway
'island's' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'central road' is the wordplay.
'central' becomes 'mid' (I've seen this in another clue).
'road' becomes 'way' (I've seen this in other clues).
'mid'+'way'='MIDWAY'
Can you help me to learn more?
(Other definitions for midway that I've seen before include "At the fifty per cent point" , "With as far to go as already travelled" , "Central point" , "Half the distance" , "Equally distant from the extremes" .)