Inspection chamber (7)
I believe the answer is:
manhole
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">inspection chamber</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 manhole that I've seen before include "Aperture to sewer, duct etc" , "Opening with a cover giving access underground" , "Underground access point" , "Access chamber to sewer or drain" , "Drain cover" .)