Stir cocktail (7)
I believe the answer is:
slammer
This clue is a double definition.
'stir' is the first definition.
(I've seen this in another clue)
'cocktail' is the second definition.
(eg an Alabama slammer)
(Other definitions for slammer that I've seen before include "One pulling off lots of tricks" , "I must be drunk in one" , "Stir" , "Prison (colloq.)" , "Prison (slang)" .)