American cold drink initially stirred then drunk (5)
I believe the answer is:
slush
'american cold drink' is the definition.
(US term for a sweet drink)
'initially stirred then drunk' is the wordplay.
'initially stirred then' becomes 's' (I can't justify this - if you can you should believe this answer much more).
'drunk' becomes 'lush' (lush is a kind of drunk).
's'+'lush'='SLUSH'
Can you help me to learn more?
(Other definitions for slush that I've seen before include "bad weather's aftermath" , "emotionalism" , "Kind of fund" , "Sentimental drivel" , "that has been frozen" .)