Lowest part (6)
I believe the answer is:
bottom
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">lowest part</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 bottom that I've seen before include "dry bed" , "Behind" , "Lowest part of anything" , "Weaver < 's backside" , "Quark's flavour" .)