A suspect surrendered Tuesday to face charges for the senseless fatal shove of an 87-year-old singing coach in Manhattan, cops said. The beloved singing coach struck her head on the ground and suffered a traumatic brain injury. She died at Bellevue Hospital a few days later. Her arraignment is pending in Manhattan Criminal Court . Gustern coached Blondie singer Debbie Harry and a Broadway cast of “Oklahoma.” Before the attack, Gustern had several pals at her apartment to rehearse for an upcoming cabaret show, a friend told the Daily News. “Her background in music theatre and opera was extraordinary, and...