Leslie, 55, of Edinburgh, denies sexual assault by intentionally touching a woman without her consent on December 5, 2008. The alleged incident is said to have happened at a Christmas party in London's West End.
The ex-broadcaster, whose full name is John Leslie Stott, sat quietly in the dock at London's Southwark Crown Court, as judge Deborah Taylor said the case would start afresh on Tuesday morning.
She told the jury: "A juror is unable to carry on so what I am going to do is, since we are in the early stages (of this case) is to discharge this jury and swear in another."
Leslie also presented Wheel of Fortune and This Morning – both on ITV - before turning his attention to business as a property developer and moving back to Edinburgh from London.