Possible Clues:

• Small cave, with religious connotations perhaps
• Picturesque cavern
• Artificial cave
• Spelunking site
• About the end of December, reached Santa's base
• Small cavern
• 'Got about a trot as a whole, by the sound of it (6)'
• (Santa's) cave
• Small attractive cave
• Flipping over the top or initially gratuitous for visiting dancer's boss?