Evacuate old island in the Mediterranean (7)
I believe the answer is:
excrete
'evacuate' is the definition.
(I know this)
'old island in the mediterranean' is the wordplay.
'old' becomes 'ex' (prefix meaning former or onetime).
'island in the mediterranean' becomes 'crete' (Crete is a Greek island).
'ex'+'crete'='EXCRETE'
(Other definitions for excrete that I've seen before include "Eliminate (from the body)" , "Defecate" , "Expel (waste) from the body" .)