Signal with no hands (4)
I believe the answer is:
omen
'signal' is the definition.
(omen is a kind of signal)
'with no hands' is the wordplay.
'with' is a charade indicator (letters next to each other).
'no' becomes 'o' (resembles 0 - 'no' can mean 'zero').
'hands' becomes 'men' (synonyms).
'o'+'men' is 'OMEN'.
(Other definitions for omen that I've seen before include "Portent, prophetic indicator" , "Warning token" , "Portent of evil" , "Auspice" , "Sign of likely future event" .)