Pre-conquest Mexican (5)
I believe the answer is:
aztec
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">pre-conquest mexican</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for aztec that I've seen before include "Pre-Spanish Mexican" , "Old empire of Mexico" , "Ancient Mexican-Indian" , "Like Montezuma?" , "Old person" .)