Polynesian island during loud New Year's Day (6)
I believe the answer is:
fijian
'polynesian' is the definition.
(Fijian is an example)
'island during loud new year's day' is the wordplay.
'island' becomes 'i' (geographical abbreviation).
'during' indicates putting letters inside.
'loud' becomes 'f' (short for forte - 'loud' in music).
'new year's day' becomes 'I Jan' (resembles 1 Jan - 1st January is New Year's Day).
'f'+'ijan'='fijan'
'i' put into 'fijan' is 'FIJIAN'.
(Other definitions for fijian that I've seen before include "Native of Suva, perhaps" , "Oceanic language" , "Islander" .)