Take power unlawfully (5)
I believe the answer is:
usurp
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">take power unlawfully</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for usurp that I've seen before include "Seize power without authority" , "Assume by force" , "Take possession of, illegally" , "Seize (throne, e.g.)" , "Arrogate" .)