Greet us somehow giving signal (7)
I believe the answer is:
'signal' is the definition.
(gesture is a kind of signal)
'greet us somehow' is the wordplay.
'somehow' indicates anagramming the letters.
'greetus' anagrammed gives 'GESTURE'.
'giving' acts as a link.
(Other definitions for gesture that I've seen before include "Movement, indication" , "Action done for show" , "Hand signal" , "Message through movement" , "Eg, shrug or wave" .)