Nothing, in Mexico (4)
I believe the answer is:
nada
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">nothing in mexico</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for nada that I've seen before include "zip" , "Nothing (US)" , "Not a sausage" , "Love" .)