Polynesian faces endless ocean with nothing in it (4)

I believe the answer is:

moai

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'polynesian faces' is the definition.
I know nothing about this answer so I cannot judge whether this works.

'endless ocean with nothing in it' is the wordplay.
'endless' means to remove the last letter.
'ocean' becomes 'main' (synonyms).
'with nothing' becomes 'o' (I can't justify this - if you can you should give a lot more credence to this answer).
'in it' is an insertion indicator.
'main' with its final letter removed is 'mai'.
'mai' placed around 'o' is 'MOAI'.

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I've seen this clue in The Independent.

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