Tremble when given a flavoured milk drink (5)
I believe the answer is:
shake
I believe this is a double definition.
'tremble' is the first definition.
(synonyms)
'a flavoured milk drink' is the second definition.
(I've seen this before)
'when given' acts as a link.
(Other definitions for shake that I've seen before include "Upset" , "Rattle" , "Jolt or agitate" , "Flavoured milk drink" , "Tremble; milk drink" .)