The most common and most likely answer to this crossword clue is the 3 letter word NOD
I've seen this crossword clue in The Times
N
O
D
More clues leading to the result NOD
- Encouraging sign from sleepy land?
- Returning academic gets sign of approval
- After word of refusal, daughter gets gesture of assent
- Approval teacher's withdrawn
- Retired academic gives signal of assent
- Retired lecturer gives green light
- Gesture with which mood becomes low?
- Signal agreement? Homer sometimes did
- Fellow brought over gives slight bow
- Be about to drop off teacher going north
Buddy explains!

The straight part
We know that "Gesture" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case gesture = nod.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does NOD mean?
NOD noun- An instance of inclining the head up and down, as to indicate agreement, or as a cursory greeting.
- A reference or allusion to something.
- A nomination.
- Approval.
- To incline the head up and down, as to indicate agreement.
- To briefly incline the head downwards as a cursory greeting.
- To sway, move up and down.
- To gradually fall asleep.
- To signify by a nod.
- To make a mistake by being temporarily inattentive or tired
- To head; to strike the ball with one's head.
- To allude to something.
- To fall asleep while under the influence of opiates.