Made a mistake about western wine (5)
I believe the answer is:
erred
'made a mistake' is the definition.
('err' can be a synonym of 'make a mistake')
'western wine' is the wordplay.
'western' becomes 'er' (I can't justify this - if you can you should give a lot more credence to this answer).
'wine' becomes 'red wine' (red is a type of wine).
'er'+'red'='ERRED'
'about' is the link.
Can you help me to learn more?
(Other definitions for erred that I've seen before include "Gone astray!" , "Made a mistake, was wrong" , "Sinned" , "Made mistakes" , "slipped up" .)