Largest Greek island (5)
I believe the answer is:
crete
'largest greek island' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for crete that I've seen before include "Large island in Med" , "Erect (anag) - Mediterranean island" , "Mediterranean island with Minoan remains" , "European location" , "Greek island, site of the Minoan civilisation" .)