COME CLEAN! Trying to head off questions about his consultants' ethics, President Clinton is requiring his top outside advisers to detail how they made their money since they've been working with him. The move comes after a G.O.P. Congressman attempted to introduce legislation requiring such disclosure to determine if influential counselors were making money lobbying the government. The four consultants affected by the directive include campaign gurus James Carville and Paul Begala as well as pollster Stan Greenberg and Mandy Grunwald. They say they have nothing to hide.