Fast affected by drink (5)
I believe the answer is:
tight
'fast' is the definition.
(I've seen this before)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for tight that I've seen before include "Miserly or blotto" , "Closely fought game" , "Strictly imposed; drunk" , "Awkward" , "Mean; firmly fixed" .)