Ladder part (4)
I believe the answer is:
rung
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">ladder part</span>' is the definition.<br/ ><span class="explanation-format__explanation">('rung' is part of 'ladder')</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for rung that I've seen before include "Phoned" , "Level in a hierarchy" , "spoke" , "Ladder's step" , "Telephoned" .)