Sloping walkway (4)
I believe the answer is:
ramp
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">sloping walkway</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 ramp that I've seen before include "Something that's not on the level" , "Short slope" , "One with an inclination" , "Sloping platform" , "Inclined path" .)