Shake cocktail later, about time (6)
I believe the answer is:
rattle
'shake' is the definition.
(I know that rattle is a type of shake)
'cocktail later about time' is the wordplay.
'cocktail' is an anagram indicator.
'about' is an insertion indicator.
'time' becomes 't' (abbreviation).
'later' anagrammed gives 'ratle'.
'ratle' going around 't' is 'RATTLE'.
(Other definitions for rattle that I've seen before include "Make someone nervous or anxious" , "led to Tweedledum and Tweedledees quarrel?" , "American snake" , "Baby's toy - racket - disconcert" , "Child's toy or kind of snake" .)