It has row upon row of rowers (6)

I believe the answer is:

bireme

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'it has row upon row of rowers' is the definition.
The definition suggests a singular noun which matches the answer.

This is the entire clue.

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(Other definitions for bireme that I've seen before include "ancient craft" , "Old ship" , "old vessel?" , "Type of ancient galley" , "Rowed boat long ago" .)

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

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