Lens holder
I believe the answer is:
rim
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">lens holder</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for rim that I've seen before include "Raised edge of a round object" , "Brink" , "Outer edge of a wheel" , "Curved edge" , "Edge or margin" .)