Smooth ale is horrible, disgusting (9)
I believe the answer is:
loathsome
'disgusting' is the definition.
('loathsome' can be a synonym of 'disgusting')
'smooth ale is horrible' is the wordplay.
'is horrible' indicates anagramming the letters.
'smooth'+'ale'='smoothale'
'smoothale' anagrammed gives 'LOATHSOME'.
(Other definitions for loathsome that I've seen before include "gross" , "Disgusting, nauseating" , "Horrid" , "Detestable" , "Repulsive" .)