Gesture of assent (3)
I believe the answer is:
nod
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">gesture of assent</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for nod that I've seen before include "Shake head in agreement" , "Signify agreement" , "Sign of agreement" , "Gesture of agreement" , "Gesture of approval with head" .)