A drug manufacturer battling accusations that it deceptively markets prescription painkillers has lost a bid to oust an opposing attorney. In a written opinion Monday, U.S. District Judge Elaine Bucklo denied a motion to disqualify Linda Singer of Cohen, Milstein, Sellers & Toll PLLC in Washington, D.C., from representing the city of Chicago in a lawsuit against makers of opium-like painkillers. Bucklo rejected the argument that Singer’s involvement in the case violated ethical standards because she …