Fine, a large man in opera (8)
I believe the answer is:
falstaff
'opera' is the definition.
(Verdi opera)
'fine a large man' is the wordplay.
'fine' becomes 'f' (abbreviation).
'large' becomes 'l'.
'man' becomes 'staff' (both can mean to work at a particular post**).
'f'+'a'+'l'+'staff'='FALSTAFF'
'in' acts as a link.
(Other definitions for falstaff that I've seen before include "Shakespeare's fat 20 ac" , "Shakespeare's rumbustious fat knight" , "Shak.'s fat knight" , "Shakespeare's Sir John" , "The Bard's fat character" .)