Mediterranean port area (4)
I believe the answer is:
acre
I believe this clue is a double definition.
'mediterranean port' is the first definition.
(I've seen this before)
'area' is the second definition.
(I've seen this before)
(Other definitions for acre that I've seen before include "Unit of land area" , "A state of W Brazil" , "Israeli seaport" , "in Western Brazil" , "region of ground" .)