Dog returned to supreme being (3)
I believe the answer is:
god
'supreme being' is the definition.
(a god is a supreme being)
'dog returned' is the wordplay.
'returned' is a reversal indicator.
'dog' backwards is 'GOD'.
'to' is the link.
(Other definitions for god that I've seen before include "Pan perhaps" , "Mars or Mercury, say" , "Divinity" , "Being upstairs" , "Superhuman being" .)