Left on Orkneys, losing last of very new breathing gear (7)

I believe the answer is:

snorkel

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'left' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe there's an association between them I don't understand?

I can't explain the remainder of the clue.

Can you help me to learn more?

(Other definitions for snorkel that I've seen before include "Surface swimmer's breathing aid" , "Swimmer's breathing tube" , "Breathing device for swimmers" , "Breathing tube for under-water swimmer" , "Diver's breathing tube" .)

I've seen this clue in The Telegraph.

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