Conqueror of Mexico (6)
I believe the answer is:
cortes
'conqueror of mexico' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for cortes that I've seen before include "Spanish conquistador, d.1547" , "Conquering Spaniard" , "Spanish parliament, sector (anag.)" , "Spanish conquistador who overthrew the Aztec emperor Montezuma, d. 1547" .)