The most common and most likely answer to this crossword clue is the 13 letter word GESTICULATION
I've seen this crossword clue in The Times
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More clues leading to the result GESTICULATION
Buddy explains!
The straight part
We know that "hand signals" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case hand signals = gesticulation.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 GESTICULATION mean?
GESTICULATION noun- The act of gesticulating, or making gestures to aid expression of thoughts, sentiments or passion.
- A gesture; a motion of the body or limbs when speaking, or in representing action or passion, and enforcing arguments and sentiments.
- An odd or fanciful motion.