Waltham - Mrs. Margaret S. (Nersesian) Clark, of Waltham, died Saturday May 13, 2006 at Newton-Wellesley Hospital. She was 91. Born in Waltham, a daughter of the late Simeon and Julia (Karkos) Nersesian, Margaret worked as an executive secretary for the Raytheon Corporation for many years. She was a graduate of Waltham High School, and lived in Newton for more than thirty years. Margaret was the wife of the late Francis B. Clark, and sister of the late Aaron, Walter, and Helen Nersesian. She leaves her children, Virginia M. Feeley and her husband, David of Marlborough, William F. Clark of Waltham and Richard J. Clark of Tyngsboro; one brother, Rudolph Nersesian of Waltham; her grandchildren, Patrick and Kelly Feeley, and many nieces and nephews. The Funeral will be held Tuesday at 9 a.m. from The Joyce Funeral Home, 245 Main Street (Rte.20), Waltham, followed by a Funeral Mass in Sacred Heart Church, 311 River Street Waltham at 10 a.m. Burial will be in Calvary Cemetery, Waltham. Visiting hours will be held Monday from 4 to 8 p.m. Memorial donations may be made to The Home for Little Wanderers, 271 Huntington Avenue, Boston, MA 02115.