Staircase post (5)
I believe the answer is:
newel
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">staircase post</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for newel that I've seen before include "Main post supporting handrail on stairs" , "domestic post" , "Post that's part of a flight of stairs" , "Central pillar of a spiral staircase" , "Yucatan native" .)