Peruvian ancestor (4)
I believe the answer is:
inca
'peruvian ancestor' 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 "Language" , "Ancient inhabitant of Peru" , "lived in Peru" , "An old Peruvian like Cain" , "Old South American native" .)