Barker's excellent ginger beer (8)
I believe the answer is:
airedale
'barker's' is the definition.
(I've seen this before)
'excellent ginger beer' is the wordplay.
'excellent' becomes 'ai' (resembles 'A1', old-fashioned term for excellent).
'ginger' becomes 'red ginger' (red hair).
'beer' becomes 'ale' (type of beer).
'ai'+'red'+'ale'='AIREDALE'
(Other definitions for airedale that I've seen before include "Canine breed" , "Barker" , "Terrier - Yorkshire area" , "Yorkshire district; breed of terrier" , "best friend?" .)