Riverside area supplying alcoholic drink that's unpleasant (6)
I believe the answer is:
meadow
'riverside area' is the definition.
'meadow' can be an answer for 'area' (meadow is a kind of area). I'm not certain of the 'riverside' bit.
'alcoholic drink that's unpleasant' is the wordplay.
'alcoholic drink' becomes 'mead' (I've seen this before).
'that's unpleasant' becomes 'ow' (expression of pain).
'mead'+'ow'='MEADOW'
'supplying' is the link.
Can you help me to learn more?
(Other definitions for meadow that I've seen before include "Tract of cultivated grassland" , "Grassed field" , "Paddock" , "Pasture" , "Low ground near river" .)