They reel up and down in play (2-3)

I believe the answer is:

yo-yos

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

I can't explain the remainder of the clue.

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(Other definitions for yo-yos that I've seen before include "Toys with spool and reel" , "Toys with pair of joined discs and string" , "Up-and-down toys on string" , "Children's toys" , "Moves up and down" .)

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

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