Scotch is what drunken revellers try, initially (6)
I believe the answer is:
thwart
'scotch' is the definition.
('thwart' can be a synonym of 'scotch')
'what drunken revellers try initially' is the wordplay.
'drunken' indicates anagramming the letters.
'initially' indicates taking the first letters.
The first letters of 'revellers try' is 'rt'.
'what' anagrammed gives 'thwa'.
'thwa'+'rt'='THWART'
'is' acts as a link.
(Other definitions for thwart that I've seen before include "check" , "cross" , "Frustrate or foil" , "Prevent from accomplishing something" , "Hinder or prevent" .)