Pier, in architecture (4)
I believe the answer is:
anta
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">pier in architecture</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 anta that I've seen before include "square column" , "architectural feature" , "PILASTER?" , "tapir" .)