Impressive grouping (5)
I believe the answer is:
array
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">impressive grouping</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 array that I've seen before include "Lay out, arrange" , "Ordered arrangement (of troops)" , "Imposing assembly" , "Marshal" , "Matrix; elaborate clothing" .)