Dog-star? Dwarf planet, anyway (5)
I believe the answer is:
pluto
'dog' is the definition.
(I have seen 'animated dog' mean 'pluto' so perhaps 'dog' could also mean 'pluto')
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for pluto that I've seen before include "Planet discovered in 1930" , "It used to be a planet" , "Roman god" , "Distant planet" , "Minor planet" .)