Possible Clues:

• Greek letter Z
• Sweater letter, perhaps
• Sixth in a pledge's recitation
• Greek character in a daze targeted
• Greek letter (___ Jones)
• It sounds last, but it's sixth
• Letter that's not really at the end of the Greek alphabet
• Last name in cinema, ___-Jones
• ___-Jones ("Chicago" star)
• Sixth-brightest star in a constellation