Main channel (6)
I believe the answer is:
artery
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">main channel</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for artery that I've seen before include "Blood-vessel" , "vessel carrying vital supply" , "Important transport route" , "blood line" , "Vessel taking blood from heart" .)