Top course for bobby (4)

I believe the answer is:

beat

I believe this is a double definition.

'top' is the first definition.
(I know this)

'course for bobby' is the second definition.
(as in a police officer's beat)

(Other definitions for beat that I've seen before include "club" , "tired" , "Worst round" , "Strike; rhythm" , "Musical rhythm" .)

I've seen this clue in The Guardian.

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