Slide unsteadily (7)
I believe the answer is:
slither
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">slide unsteadily</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 slither that I've seen before include "Slide, slip" , "Slide unsteadily" , "Quietly advance" , "Move like a snake" , "Slide (like a snake)" .)