Italian banker's Oscar-nominated part (4)
I believe the answer is:
arno
'italian banker's' is the definition.
'arno' can be an answer for 'banker's' (I've seen this before). I am not certain of the 'italian' bit.
'oscar-nominated part' is the wordplay.
'part' indicates the answer is hidden within the clue.
'ARNO' can be found hidden inside 'oscar nominated'.
(Other definitions for arno that I've seen before include "Italian river" , "Florence's river" , "River of 4 down?" , "Pisa's river" , "River in central Italy" .)