Possible Clues:

• Illusionist's feat
• Magic trick that affects the answers to starred clues
• Part of a magic show, and the key to understanding this puzzle’s one-word clues
• Trick of being suddenly nowhere to be found ... or an apt description of victory for a 59-Down player?
• Magician's feat, and a hint to the starts of 19-, 24- and 45-Across
• About to withdraw bill that 21 is known for?
• What something goes *poof* in
• Part of a magic show
• Exam that's losing popularity in high schools?
• Part of a magician's performance