Possible Clues:

• 19-Across request
• Security checkpoint item
• It says who the bearer is
• Proof that you're who you say you are
• Wallet item
• Driver's license, often
• Pilot's airport security requirement (2 words)
• Personal identification document with photograph, age, etc
• Proof at the door
• Detective returns for birthday ¿ that'll tell you how old he is