Large Indonesian island (4)
'large indonesian island' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sumatra that I've seen before include "Second largest Indonesian island" , "part of Indonesia" , "Large Indonesian island" , "Some land" , "A US mart on an Indonesian island?" .)
(Other definitions for java that I've seen before include "Large island; coffee type" , "Its capital is Jakarta" , "Indonesian island - computer programming language" , "Jakarta's island" , "Jakarta on this island" .)