Silent "yes” (3)
I believe the answer is:
nod
'silent yes' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for nod that I've seen before include "Agree non-verbally" , "What Homer may sometime do" , "overlook something" , "Sign of assent or salutation" , "Indicate assent or recognition" .)