Gulf sheikhdom (5)
I believe the answer is:
dubai
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">gulf sheikhdom</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 dubai that I've seen before include "Gulf territory" , "Gulf city/state" , "Arab city" , "Country" , "Port city of UAE" .)