Tiresome type carrying note round Pacific island (6)
I believe the answer is:
'pacific island' is the definition.
(I've seen this before)
'tiresome type carrying note round' is the wordplay.
'tiresome type' becomes 'bore'.
'carrying' is an insertion indicator.
'note' becomes 'n' (abbreviation).
'round' becomes 'o' (round can mean a round object).
'bore' enclosing 'n' is 'borne'.
(Other definitions for borneo that I've seen before include "West Pacific island" , "The world's third-largest island" , "Largest Asian island" , "Island, part of the Malay archipelago" , "Oberon on the large Asian island" .)