Undergrowth (5)
I believe the answer is:
scrub
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">undergrowth</span>' is the definition.<br/ ><span class="explanation-format__explanation">(scrub can mean undergrowth or vegetation)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for scrub that I've seen before include "Clean, low vegetation" , "Rub hard - low vegetation" , "clean-up" , "Clean by rubbing really hard" , "Drop" .)