Sign of agreement (3)
I believe the answer is:
nod
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">sign of agreement</span>' is the definition.<br/ ><span class="explanation-format__explanation">(a nod can indicate agreement)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for nod that I've seen before include "Acknowledge by gesture" , "Indicate agreement (or sleepiness!)" , "Signal with the head" , "Drowse" , "Agree non-verbally" .)