Coal mine (8)
I believe the answer is:
colliery
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">coal mine</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for colliery that I've seen before include "Coal mine" , "Where a coalminer goes to work" , "Coalmine and surrounding buildings" , "Grimethorpe?" , "Pit" .)