Bankrupt following black bear (5)
I believe the answer is:
'bear' is the definition.
(I know that bruin is a type of bear)
'bankrupt following black' is the wordplay.
'bankrupt' becomes 'ruin' (synonyms).
'following' says to put letters next to each other.
'black' becomes 'b' (as in pencil classifications).
'ruin' put after 'b' is 'BRUIN'.
(Other definitions for bruin that I've seen before include "Archetypal name for a bear" , "Conventional name for a bear" .)