Shake like a snake? (6)
I believe the answer is:
rattle
I believe this clue is a double definition.
'shake' is the first definition.
(I know that rattle is a more specific form of the action shake)
'a snake?' is the second definition.
(I have seen 'American snake ' mean 'rattle' so perhaps 'snake' could also mean 'rattle')
'like' is the link.
(Other definitions for rattle that I've seen before include "Vibrate noisily" , "Put out" , "Infant's toy" , "Lively old song - Shake, . . . . . . and roll" , "Baby's toy - racket - disconcert" .)