Pupil surrounder (4)
I believe the answer is:
iris
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">pupil surrounder</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for iris that I've seen before include "Fleur-de-lis" , "Garden flower - part of eye" , "Flag,flower and part of the eye" , "Female" , "Flag - flower - girl" .)