Sergio —, director of 1984 film drama Once Upon a Time in America (5)
I believe the answer is:
leone
(Other definitions for leone that I've seen before include "Sierra ___ (West African country) - Sergio ___ (film director)" , "Sergio ___ , Italian film director d. 1989" , "African rhino" , "Sierra -, W. Afr. state" , "Sergio --, spaghetti western director" .)