Diana, a butcher, minced steak (13)
I believe the answer is:
chateaubriand
'steak' is the definition.
(Chateaubriand is an example)
'diana a butcher minced' is the wordplay.
'minced' indicates anagramming the letters.
'diana'+'a'+'butcher'='dianaabutcher'
'dianaabutcher' with letters rearranged gives 'CHATEAUBRIAND'.
(Other definitions for chateaubriand that I've seen before include "diplomat" , "French writer" , "portion of meat" , "Fr. writer; fillet steak" , "Thick beef steak fillet" .)