Drip fermented a keg ale (7)
I believe the answer is:
leakage
'drip' is the definition.
(thesaurus)
'fermented a keg ale' is the wordplay.
'fermented' indicates anagramming the letters.
'a'+'keg'+'ale'='akegale'
'akegale' with letters rearranged gives 'LEAKAGE'.
(Other definitions for leakage that I've seen before include "Accidental spill" , "Unwelcome flow" , "Accidental escape (of a liquid or gas)" , "Unwanted discharge of fluid" , "Unwanted escape (eg of water or information)" .)