Christmas worker that is on board ship snaps (7)

I believe the answer is:

selfies

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'snaps' is the definition.
Both the definition and answer are plural nouns.
Maybe they are linked in a way I don't understand?

'christmas worker that is on board ship' is the wordplay.
'christmas worker' becomes 'elfie' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'that is on board' indicates putting letters inside (inserted letters are taken on board).
'ship' becomes 'SS' (prefix in ship names eg SS Great Britain).
'elfie' put within 'ss' is 'SELFIES'.

Can you help me to learn more?

I've seen this clue in The Mirror.

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