Crossword Genius

What goes round, up, or down? (7)

Ross

I believe the answer is:

rotator

I'm a little stuck... Click here to teach me more about this clue!

'down?' is the definition.
Both the answer and definition are singular nouns.
Maybe there's a link between them I don't understand?

'what goes round up or' is the wordplay.
I cannot quite understand how this works, but
'round' could be 'o' (o is a circular letter) and 'o' is located in the answer.
'or' is present in the answer.
This explanation may well be incorrect...

Can you help me to learn more?

(Other definitions for rotator that I've seen before include "One goes round" , "Something turning" , "Revolver" , "this one is for turning" , "Something that turns" .)

I've seen this clue in the Sydney Morning Herald.
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