Finished with butter, I smoked beef (8)
I believe the answer is:
pastrami
'smoked beef' is the definition.
(type of smoked meat)
'finished with butter i' is the wordplay.
'finished with' becomes 'past' (past can mean forgotten or finished).
'butter' becomes 'ram' (a ram is something which 'butts').
'past'+'ram'+'i'='PASTRAMI'
(Other definitions for pastrami that I've seen before include "Tapered tuck; missile" , "Spicy smoked beef" , "Spiced sliced beef" , "Thinly sliced beef" , "Highly seasoned cut of smoked beef" .)