Reverses and runs down (6)

I believe the answer is:

knocks

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But I can't explain it at all! Could you help me understand?

(Other definitions for knocks that I've seen before include "Raps; criticises" , "criticisms" , "Strikes with a sharp blow or finds fault with" , "Reversals" , "Raps on the door" .)

I've seen this clue in The Times.

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