Peruvian progenitor (4)
I believe the answer is:
inca
'peruvian progenitor' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for inca that I've seen before include "Original Peruvian" , "Language" , "Pre-conquest South American Indian" , "Old Peruvian people" , "Old Peruvian descended from Cain" .)