Terribly blasé about fur (5)
I believe the answer is:
sable
'fur' is the definition.
(I know that sable is a type of fur)
'terribly blase' is the wordplay.
'terribly' is an anagram indicator.
'blase' with letters rearranged gives 'SABLE'.
'about' acts as a link.
(Other definitions for sable that I've seen before include "(Fur from) small carnivore" , "fur coat" , "Bales of expensive Russian fur" , "Literary black" , "Fur - heraldic black" .)