Nahuatl language (5)
I believe the answer is:
aztec
'nahuatl language' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for aztec that I've seen before include "old American" , "Montezuma ruled this empire" , "American people" , "Ancient inhabitant of Mexico before Spanish conquest" , "Ancient Mexican-Indian" .)