Separates into stacks (5)
I believe the answer is:
sorts
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">separates into stacks</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 sorts that I've seen before include "classes" , "Systematically arranges" , "Categories" , "Places in correct or desired sequence" , "Classifies" .)