The dog bounds round in, coming back (7)
I believe the answer is:
spaniel
'the dog' is the definition.
(spaniel is a kind of dog)
'bounds round in coming back' is the wordplay.
'bounds' becomes 'leaps' ('leap' can be a synonym of 'bound'**).
'round' means one lot of letters goes inside another.
'coming back' says the letters should be written backwards.
'leaps' going around 'in' is 'leinaps'.
'leinaps' reversed gives 'SPANIEL'.
(Other definitions for spaniel that I've seen before include "Dog - leaps in (anag)" , "Dog with long silky coat" , "Type of dog" , "Animal" , "Dog found among the alpines" .)