When the animal turns, run (4)

I believe the answer is:

flow

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'run' is the definition.
(I know that run can be written as flow)

I can't explain the rest of the clue.

(Other definitions for flow that I've seen before include "Fluid motion" , "Run or move like a liquid" , "Move steadily" , "Run smoothly" , "Uninterrupted stream" .)

I've seen this clue in the Evening Standard.

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