…an island Oberon represented (6)
I believe the answer is:
borneo
'an island' is the definition.
(Borneo is an example)
'oberon represented' is the wordplay.
'represented' indicates an anagram.
'oberon' is an anagram of 'BORNEO'.
(Other definitions for borneo that I've seen before include "Island shared by Malaysia and Indonesia" , "West Pacific island" , "Largest Asian island" , "Largest island of Asia" , "Island, part of the Malay archipelago" .)