Bygone Peruvian (4)
I believe the answer is:
inca
'bygone peruvian' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for inca that I've seen before include "Former emperor" , "Ancient Peruvian like Cain" , "Old person in race" , "who lived in S America" , "Member of ancient Peruvian tribe" .)