At Harvard University, he rowed on the crew for Lowell House, wrote for the Harvard Crimson, and was a member of the Fly Club.
He graduated in 1961 with a degree in government, then served in the Navy for four years.
After military service, Mr. Clark earned a degree from the University of Pennsylvania Law School and joined Ballard Spahr. While there, he contributed pro bono work to those unable to afford counsel.
Mr. Clark was a first cousin of former Mayor and U.S. Sen. Joseph S. Clark. By working for the senator during two summers in Washington, Mr. Clark developed an interest in politics, history, and public service, his family said.
Mr. Clark and his cousin Michael Clark Rockefeller, son of the former vice president and New York governor, were close. The cousins attended college together, went on summer trips, and worked on a cattle ranch in Venezuela.
In 1961, Michael Rockefeller, 23, went to New Guinea to film indigenous people. On Nov. 17, during a trip between villages, his catamaran capsized in high seas. He swam for shore, but his body was never found despite an intensive search in which his father participated. The tragedy devastated the Clark and Rockefeller families.
Among Mr. Clark's great-grandfathers was Lord John Arbuthnot Fisher, admiral of the British navy, who was responsible for construction of the Dreadnought, the first modern battleship in the British fleet prior to World War I.
Mr. Clark served as a volunteer board member for the Philadelphia City Institute and the Widows Corp., a nonprofit that supports the families of Episcopal clergy. He also served as president of the board of Historic Rittenhouse Town.
An enthusiastic gardener, Mr. Clark was on the boards of the Pennsylvania Horticultural Society and Bartram's Garden.
His wife of 47 years, the former Virginia Bradley, said her husband's roses and azaleas were legendary, and his vegetables "fed the whole community."
In person, she said, "he was a really good listener. What he said really counted. He had a nice sense of humor, but not at somebody else's expense."
He also is survived by son Ned; daughter Allison; and four grandchildren.
A memorial service and reception will be at 11 a.m. Saturday, Nov. 16, at the chapel at St. David's Episcopal Church, 763 S. Valley Forge Rd., Wayne. Burial is private.
Donations may be made to the National Parkinson Foundation, 800 Spruce St., Philadelphia 19107, or via www.parkinson.org.