All are reeling before end of stale beer (4,3)
I believe the answer is:
real ale
'beer' is the definition.
(type of beer)
'all are reeling before end of stale' is the wordplay.
'reeling' is an anagram indicator.
'before' says to put letters next to each other.
'end of' indicates one should take the final letters.
The final letter of 'stale' is 'e'.
'all'+'are'='allare'
'allare' is an anagram of 'realal'.
'realal'+'e'='REAL ALE'
(Other definitions for real ale that I've seen before include "CAMRA interest" , "booze" , "Pub drink" , "Beer fermented in cask, served without carbon dioxide" , "Objective of campaign" .)