The judge overseeing former President Donald Trump’s indictment on charges of illegally retaining national defense information issued an order Thursday instructing any lawyer who wants to take part in the case to start the process of obtaining a security clearance to handle classified material by early next week. The brief order by the federal judge, Aileen M. Cannon, instructed the lawyers to reach out to the Litigation Security Group at the Justice Department by Tuesday to “expedite” the proce