Gestures of assent (4)
I believe the answer is:
nods
'gestures of assent' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for nods that I've seen before include "Indicates assent" , "Shows assent" , "Affirmative gestures" , "Non-verbal indications of assent" , "Agrees" .)