Row, level (4)
I believe the answer is:
tier
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">row</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(a tier is a row of things)</span><br/ ><br/ >'<span class="explanation-format__original">level</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I know that level can be written as tier)</span><br/ ><br/ ></span>
(Other definitions for tier that I've seen before include "Layer, rank" , "Rite (anag.)" , "Rite for a rank" , "One of two or more rows" , "Row, level" .)