Eastern ruler (6)
I believe the answer is:
sultan
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">eastern ruler</span>' is the definition.<br/ ><span class="explanation-format__explanation">(title for a royal in some Muslim countries)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for sultan that I've seen before include "Sovereign of a Muslim state" , "Turkish ruler" , "One governs" , "Ottoman sovereign" , "Chicken" .)