Judder (9)
'judder' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for shake that I've seen before include "moment" , "Quiver" , "Frothy milk drink" , "Tremble; milk drink" , "Judder" .)
(Other definitions for vibration that I've seen before include "Pulsation" , "Quick back and forward movement" , "Palpitation, oscillation" , "fast pulse?" , "Rapid to-and-fro motion" .)