Biological subdivision (5)
I believe the answer is:
genus
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">biological subdivision</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 genus that I've seen before include "Category above species (Biology)" , "Group of plants with common characteristics" , "species grouped together" , "Taxonomic grouping" , "Part of the family" .)