Ancient civilisation of Peru (4)
I believe the answer is:
inca
'ancient civilisation of peru' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for inca that I've seen before include "Pyramid builders" , "Atahualpa was" , "Language" , "Andean culture" , "An old Peruvian like Cain" .)