Plant's climbing organ (7)
I believe the answer is:
tendril
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">plant's climbing organ</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 tendril that I've seen before include "Clinging part of a plant" , "Coiling shoot of climbing plant" , "Natural thread climbing plants produce to attach to a support" , "Climbing plant's supporter" , "Twisted lock of hair" .)