Ladder section (4)
I believe the answer is:
rung
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">ladder section</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 rung that I've seen before include "Step up the ladder - called for" , "Ladder's step" , "Horizontal bar in ladder" , "support for foot" , "Part of a ladder" .)