Possible Clues:

• Ice-cream buy
• Go off
• Palindromic musical genre
• Double you over the easel to go like this
• Genre for 1- & 22-Across, 22- & 26-Across, 26- & 46-Across and 46- & 49-Across
• Moniker for an old man
• Explosive sound
• Burst into song?
• Soda, elsewhere in the world
• Sound made by opening bottle of hock