Certain of success out tippling? Au contraire! (4,3,3)
I believe the answer is:
home and dry
I'm afraid I can't even guess how this answer relates to the clue.
Can you help me to learn more?
(Other definitions for home and dry that I've seen before include "Successfully arrived at the end of a difficult enterprise" , "In a position to reach a goal without much further difficulty" , "Definitely safe or successful" , "Having achieved one's objective" .)