Possible Clues:

• Central part
• See 1
• Take heart. With two days will be within distance
• (A person's) waist
• With 44-Down, educational stage ... or a hint to the contents of 18-, 22-, 47- and 53-Across
• Equally distant from the extremes
• Centre or core
• It takes ages to be 6 down
• There's no end of it when it's so long about the divine
• One's disrespectfully raised one who's not 18 to embrace cheat, heading to the 22