Possible Clues:

• Tune heard on leaving London behind
• One's backside in France
• The behind behind you
• (French?) behind
• French back behind London hearing an old tune
• Fourteen down's behind Danny Boy broadcast (abridged version)
• 11 down with this behind for the tune of 1 down (8)
• Bottom of French class
• Sounds as if one might find Danny Boy in this back side of London, by the sound of it (8)
• Behind the French