Study Greek island for real (8)
I believe the answer is:
concrete
'real' is the definition.
(associated in meaning)
'study greek island' is the wordplay.
'study' becomes 'con' (con can informally mean to study).
'greek island' becomes 'crete' (Crete is a Greek island).
'con'+'crete'='CONCRETE'
'for' acts as a link.
(Other definitions for concrete that I've seen before include "Specific - building material" , "Definite; building material" , "Real; building material" , "Firm" , "Strong, hard, building material" .)