Male hormone (12)
I believe the answer is:
testosterone
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">male hormone</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 testosterone that I've seen before include "Male sex hormone" , "male driver?" , "stimulator of particular sexuality" , "It might make a man of you" .)