Power-crazed person (12)
I believe the answer is:
megalomaniac
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">power-crazed person</span>' is the definition.<br/ ><span class="explanation-format__explanation">(someone obsessed with power)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for megalomaniac that I've seen before include "Pathological egotist" , "Power-mad individual" , "One thinking he is great" , "Person with delusions of power" , "Act of controlling by force" .)