Rule as king (5)
I believe the answer is:
reign
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">rule as king</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 reign that I've seen before include "Wield the sceptre" , "Period of the rule of a sovereign" , "Rule - dominate" , "Occupy the throne" , "Hold sway, rule" .)