Royal headdress (5)
I believe the answer is:
crown
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">royal headdress</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for crown that I've seen before include "Highest part; coin" , "Monarch's headgear" , "King" , "Headdress, coin" , "Old coin; whack on head" .)