Largest of the Marianas (4)
I believe the answer is:
guam
'largest of the marianas' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for guam that I've seen before include "Largest of the Mariana Islands" , "US island east of the Philippines" , "Island in the West Pacific" , "US unincorporated territory in the western Pacific" , "North Pacific island, base for the US navy and air force" .)