Resident of ancient Mexico (5)
I believe the answer is:
mayan
'resident of ancient mexico' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for mayan that I've seen before include "Cent. American tongue" , "Central American Indian language" , "from an ancient culture" , "of a bygone civilisation" , "Former native of Central America" .)