Acts on a revolving stage? (5)

I believe the answer is:

turns

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

'acts on' is the definition.
'turns' can be an answer for 'acts'. I am not sure about the 'on' bit.

I cannot understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for turns that I've seen before include "Moves in a new direction" , "Starts" , "Revolves" , "Rotates" , "Changes direction" .)

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

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