Martinet (14)
I believe the answer is:
disciplinarian
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">martinet</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for disciplinarian that I've seen before include "One who exercises firm control" , "One keeping strict control" , "Martinet" .)