The head of the Secret Service, a retired presidential detail leader who was given the assignment of shoring up the agency in a period of crisis, is leaving his post, a little more than two years after arriving in one of Washington's toughest jobs. Joseph P. Clancy, whom President Barack Obama summoned back from the private sector in late 2014 amid a string of security breaches and employee misconduct in the agency, said it's now time to retire for good. He alerted the White House last week of his plans to step down March 4, giving President Trump the chance...