Part of the Malay Archipelago (6)
I believe the answer is:
borneo
'part of the malay archipelago' is the definition.
('Borneo' is part of 'malay archipelago')
This is all the clue.
(Other definitions for borneo that I've seen before include "Large E. Indies island" , "country" , "Largest island of the Malay archipelago" , "West Pacific island" , "The world's third-largest island" .)