Dog advice when the leads are about so long (6-3)

I believe the answer is:

toodle-pip

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'so long' is the definition.
(I know that so long can be written as toodle-pip)

I can't explain the rest of the clue.

(Other definitions for toodle-pip that I've seen before include "Farewell remark - dipole top (anag)" , "Take care" , "so long" , "Farewell (informal)" , "Goodbye (dated)" .)

I've seen this clue in The Daily Express.

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