Where the Ko'olau range is located (4)
I believe the answer is:
oahu
'where the ko'olau range is located' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for oahu that I've seen before include "Pacific island" , "Honolulu's island" , "Chief island of Hawaii" , "popular Pacific location" , "Hawaiian island" .)