Possible Clues:

• Place for a nonurgent issue, and what can be found at the end of 16-, 24-, 37-, or 53- Across?
• Place for low-priority items
• Warm place to keep pot simmering, not requiring immediate attention
• *Figurative place for deferred options
• Low-priority place, and a hint to the starred answers' indicated letters
• Sleeping sunbather, at times?
• Place for low-priority issues
• Part of the heating system not requiring immediate attention
• Angel about to go to hell — or limbo?
• A water heater might be low priority