Oahu greeting (5)
I believe the answer is:
aloha
'oahu greeting' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for aloha that I've seen before include "16 across in Hawaii" , "Hawaiian hello or goodbye" , "Hawaiian farewell" , "A Polynesian hello or goodbye" , "A Hawaiian welcome" .)