In Samoa, hugely popular Pacific location (4)
I believe the answer is:
oahu
'popular pacific location' is the definition.
(I've seen this before)
'in samoa hugely' is the wordplay.
'in' says the answer is hidden in the clue.
'OAHU' is hidden in the letters of 'samoa hugely'.
(Other definitions for oahu that I've seen before include "Hawaiian island" , "Chief island of Hawaii" , "popular Pacific location" , "Honolulu's island" , "Pacific island" .)