— Sea, that part of the Indian Ocean west of the Arafura Sea and north of Australia (5)
I believe the answer is:
timor
(Other definitions for timor that I've seen before include "Island north of Australia" , "East Indies island NW from Darwin" , "Eastern island" , "Island of the Malay Archipelago" , "East . . . . ., became independent of Indonesia in 2002" .)