Vessel with full complement of mates (3)

I believe the answer is:

ark

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'vessel' is the definition.
(ark is a kind of vessel)

I cannot understand how the remainder of the clue works.

(Other definitions for ark that I've seen before include "Noah's boat" , "protection for couples that rose in bad weather" , "Biblical vessel" , "Noah's vessel - in which the Torah scrolls are kept" , "Animal rescue transport" .)

I've seen this clue in The Globe and Mail.

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