Rootstock (7)
I believe the answer is:
rhizome
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">rootstock</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for rhizome that I've seen before include "Root" , "Underground rootstock of a plan" , "Type of rootstock" , "that supplies stock" , "part of plant" .)