Long passage (8)
I believe the answer is:
corridor
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">long passage</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 corridor that I've seen before include "Long passageway" , "Train's aisle" , "Passageway in building" , "Enclosed passageway wtih rooms off" , "Indoor passage" .)