Science of plant life (6)
I believe the answer is:
botany
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">science of plant life</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for botany that I've seen before include "Science of plants" , "The scientific study of plants" , "Plant study" , "the name of a bay" , "type of wool" .)