Pope's triple crown (5)
I believe the answer is:
tiara
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">pope's triple crown</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 tiara that I've seen before include "Half-crown?" , "Decorative headgear" , "Decorative headband" , "special headgear" , "Crescent-shaped headdrsss or Pope's diadem" .)