Not the sole order that a dog obeys (4)

I believe the answer is:

heel

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'sole order that a dog obeys' is the definition.
'heel' can be an answer for 'sole' (thesaurus). I'm unsure of the rest of the definition.

I don't understand the remainder of the clue.

Can you help me to learn more?

(Other definitions for heel that I've seen before include "Bounder; part of foot" , "horrible person" , "A cad and a bounder!" , "Back part of the foot" , "unpleasant type" .)

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

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