Corrected - Obama chooses Clancy to be Secret Service director

(Corrects to "Director" from "Doctor" 5th paragraph) WASHINGTON (Reuters) - President Barack Obama has chosen Joseph Clancy as the new head of the U.S. Secret Service, the White House said on Wednesday, after a series of high profile security lapses led to a shake-up in the troubled agency's leadership. Director Julia Pierson stepped down in October after an embarrassing Sept. 19 White House breach in which a man carrying a knife jumped the fence and ran into the executi