Be on the brink (6)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">be on the brink</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for teeter that I've seen before include "Wobble as though about to fall" , "Totter, wobble" , "Sway back and forth on the edge" , "Sway back and forth, on the brink perhaps" , "See-saw on the edge" .)