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"That is not the way democracy works," Clinton said as she fielded apologies and questions Thursday from Jerry Simms, the outgoing chairman of the host Institute of Scrap Recycling Industries.

"People bring their beliefs and their concerns to the table, and work them through," Clinton said.

Meanwhile, a woman was taken into federal custody after admitting she threw the shoe. She didn't say why she did it.

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"Is that somebody throwing something at me?" Clinton said after the object flew past her on the stage at the Mandalay Bay resort. "Is that part of Cirque de Soleil?"

Most in the audience of more than 1,000 people understood the reference to the popular series of Las Vegas Strip shows featuring acrobats, magic and whimsy.

"My goodness, I didn't know that solid waste management was so controversial," Clinton laughed. "Thank goodness she didn't play softball like I did."

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Brian Spellacy, U.S. Secret Service supervisory special agent in Las Vegas, said the woman in custody was being questioned and would face criminal charges. Spellacy declined to identify the woman.

Spellacy and a spokeswoman for U.S. Attorney Daniel Bogden said it wasn't immediately clear what charges she would face.

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Shoe thrown at Hillary Clinton