Tiny aperture (7)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">tiny aperture</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 pinhole that I've seen before include "This may let in a chink of light" , "little gap" , "Small puncture" , "Tiny aperture" .)