South Seas islands (7)
I believe the answer is:
'south seas islands' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for oceania that I've seen before include "Polynesia, Micronesia and Melanesia" , "Islands of the south Pacific -- a neo-CIA (anag)" , "part of the Pacific" , "The Pacific islands taken together" , "Pacific island area" .)