Following Guinness, almost drunk (7)
I believe the answer is:
ensuing
'following' is the definition.
(I've seen this before)
'guinness almost drunk' is the wordplay.
'almost' means to remove the last letter (almost the whole word is kept).
'drunk' is an anagram indicator.
'guinness' with its final letter taken off is 'guinnes'.
'guinnes' with letters rearranged gives 'ENSUING'.
(Other definitions for ensuing that I've seen before include "Resulting" , "Following as a result" , "Following as a consequence" , "Immediately following" , "Happening afterwards" .)