Main drain (5)
I believe the answer is:
sewer
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">main drain</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 sewer that I've seen before include "Drain - seamstress?" , "Embroiderer; soil pipe" , "Plier of needle; drain" , "One working with material?" , "Underground waste pipe" .)