Mexican monetary unit (4)
I believe the answer is:
peso
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">mexican monetary unit</span>' is the definition.<br/ ><span class="explanation-format__explanation">(peso is a kind of mexican monetary unit)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for peso that I've seen before include "Foreign currency" , "Chilean currency" , "Currency of Mexico" , "Manuel's fiver" , "Mexican coin" .)