Something hard about a role for French emperor (9)
I believe the answer is:
bonaparte
'french emperor' is the definition.
(Napoleon Bonaparte)
'something hard about a role' is the wordplay.
'something hard' becomes 'bone'.
'about' means one lot of letters goes inside another.
'role' becomes 'part' (eg a part or role in a film).
'a'+'part'='apart'
'bone' placed around 'apart' is 'BONAPARTE'.
'for' acts as a link.
(Other definitions for bonaparte that I've seen before include "Napoleon's family name" , "Napoleon family" , "Extremely delicate and light" , "Old leader" , "Exiled emperor" .)