Stagger, be unsteady (6)
I believe the answer is:
totter
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">stagger</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">be unsteady</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ ></span>
(Other definitions for totter that I've seen before include "Waver and threaten to fall" , "Scrap dealer" , "Be unsteady on one's feet" , "rock" , "I add" .)