Routes mentioned in Greek island (6)
I believe the answer is:
rhodes
'greek island' is the definition.
(I've seen this before)
'routes mentioned' is the wordplay.
'routes' becomes 'roads' ('road' can be a synonym of 'route').
'mentioned' shows a homophone (sound like).
'roads' is a homophone of 'RHODES'.
'in' is the link.
(Other definitions for rhodes that I've seen before include "Greek island, ten miles off the Turkish coast" , "Horsed around on the Greek island" , "British imperialist; Greek island" , "Dock for undersea craft" , "She and Rod have a Greek holiday here" .)