Mickey Mouse sort of pet, but heavenly! (5)

I believe the answer is:

pluto

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'mickey' is the definition.
The answer and definition can be both people as well as being singular nouns.
Perhaps you can see a link between them that I can't see?

I don't understand the remainder of the clue.

Can you help me to learn more?

(Other definitions for pluto that I've seen before include "Solar System's smallest planet" , "Planet - cartoon dog - God of the Underworld" , "animated dog" , "Distant planet" , "Remote member of solar system" .)

I've seen this clue in the Evening Standard.

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