Related Clues:

• Foul language user?
• Field zebra
• N.B.A. official
• Official with a whistle
• Caller of 39-Across
• Court judge
• He rules over balls
• Whistling zebra?
• One who might call holding
• Two-minute warning giver
• "Offside" official, for short
• He may OK a KO
• Arbiter with a whistle
• B-ball arbitrator
• One who may OK a KO