Barman tours clubs with a European bunch of boozers (7)
I believe the answer is:
Here is my best explanation:
'bunch of boozers' is the definition.
(participants in Roman festival Bacchanalia)
'barman tours clubs with a european' is the subsidiary indication.
'barman' becomes 'bach' (Bach, a composer responsible for bars of music**).
'tours' indicates putting letters inside.
'clubs' becomes 'c' (abbreviation used in card games such as bridge).
'with' says to put letters next to each other.
'european' becomes 'e' (abbreviation e.g. EU).
'bach' enclosing 'c' is 'bacch'.
(Another definition for bacchae that I've seen is "The --, tragedy by Euripedes".)