Messy drinker? George Best was great one! (8)
I believe the answer is:
dribbler
'messy drinker?' is the definition.
The answer and definition can be both people as well as being singular nouns.
Perhaps you can see an association between them that I don't see?
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for dribbler that I've seen before include "Skilful ball player" , "Footballer" , "acts like a baby?" , "one with teething problems?" , "one who can keep control of Balls?" .)