Motions get users worried (8)
I believe the answer is:
gestures
'motions' is the definition.
(gesture is a kind of motion)
'get users worried' is the wordplay.
'worried' indicates anagramming the letters.
'get'+'users'='getusers'
'getusers' with letters rearranged gives 'GESTURES'.
(Other definitions for gestures that I've seen before include "Expressive movements" , "waves" , "Movements to express something" , "Expressive motions" , "Make signs with hand movements" .)