Brilliant group of puppies following good year (8)
I believe the answer is:
glittery
'brilliant' is the definition.
'group of puppies following good year' is the wordplay.
'group of puppies' becomes 'litter' (group of puppies born at the same time).
'following' says to put letters next to each other.
'good' becomes 'g' (abbreviation).
'year' becomes 'y'.
'litter' put after 'g' is 'glitter'.
'glitter'+'y'='GLITTERY'
(Other definitions for glittery that I've seen before include "snazzy" , "Sparkly" , "Brightly shining" .)