Possible Clues:

• Youngster's heartily sick, given this sort of equation!
• Die-shaped
• Solid apprentice pronouncedly icy
• Measured in 3-D
• ___ zarconia (imitation diamond)
• Relating to volume
• Raised to the third power
• Like sugar lumps a youngster imprudently consumes for starters
• Sort of equation making youngster heartily sick?
• 3-D