Possible Clues:

• One holding up the show?
• Concert-in-the-park site
• *Outdoor concert venue
• Platform for the concert
• Crowd get up where musicians play
• After prohibition, 500 bear cost of music platform
• Stall supporting group that might be on the prom?
• Rings head of theatre as well as players here
• They might have a try at getting on abreast of late, perhaps, with a yo, ho, ho!