Having been shaken, may get drunk! (8)
I believe the answer is:
cocktail
'drunk' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for cocktail that I've seen before include "Screwdriver, for example" , "Possibly old-fashioned" , "Manhattan, perhaps" , "Mixed alcoholic drink or prawn appetiser" , "old-fashioned in America" .)