If, as her beloved F. Scott Fitzgeraid said, there are no second acts in American lives, Marion Clark put on a great first one.

Marion Clark, 35, was killed Sunday in an accident at the Iosco County, Mich., airport - she walked into a propeller after a holiday jaunt with friends in a light plane.

She had joined The Washington Post in 1966 as a copy aide, rising to reporter at Potomac magazine, then, in 1972, managing editor, and last year, to editor. She would have edited The Washington Post Magazine, Potomac's replacement, which she helped design. The first issue will be out Sunday.

But that was the last thing people talked about when the phones started ringing Sunday night and the Labor Day holiday ended for the ones who knew her.

She was extraordinarily modest. She credited all her successes to chance, or her superiors' foolishness. An unexpected present could make tears rise in her eyes.

This would seem to contradict her case and delight in the prominence she and Post reporter Rudy Maxa had won by exposing the Elizabeth Ray - Wayne Hays scandal. With Maxa also she was co-author of the book "Public Trust, Private Lust - Sex, Power and Corruption on Capitol Hill."

But then, everybody always said she was complicated: a Fitzgerald romantic "The Crack-Up" was nearly a breviary); a Waugh cynic "Scoop" was her journalism text); and a Tom Wolfe savorer and satirizer of post-war American popular culture, to list three of her favorite authors.

In a city ruled by the gray facts of politics - she said Washington was "namby-pamby" - Clark lived with the style and grace of places where things "go glimmering," as Fitzgerald said. Her Ashmead Place house was the site of parties whose elan placed her, in Washington gossip, high in the "Junior Glitter Set."

Maxa liked to tease that her family crest should read "More Champagne."

"Her diet and rest habits were the despair of her friends," said Post style section editor Shelby Coffey, her predecessor as Potomac editor.

But: "She said she enjoyed her own way of doing things and besides, she often said, she was going to die young and would't have to worry about the nitrite and nicotine 30 years later after. She would always grin when she threw out that argument-ender about dying young. She loved that little act and it was all the self-mocking romanticism that made her, as writer and woman, and innocent treasure."

Conversely, she could swear to another coworker that her secret passion was to be a military officer's wife, with all the protocol and rigidity of that life.

And it was the deep-fried-neon-nitro-fueled weight-watching mid-America that inspired the acute creative intelligence whose existence she would deny while writing, as she did in June in a review of a book chronicling the McDonald's hamburger empire: "I just scarfed down a bag of McDonald's fries - that makes close to 500 bagsful I've eaten in life - and had a sudden Emersonian flash of plugging into the Golden Arches Oversoul."

Most of all, though, it was her empathy, her understanding, that people remember.

Maxa recalled: "Marion could make you feel like you had known her for years in just five minutes, and sources trusted her, leveled with her and gave details that added to every story."

Television columnist John Carmody talked about her "remembering birthdays or other anniversairies with absolutely stunning, appropriate gifts."

She once ordered a handcrafted leather set of Mickey Mouse ears for a Post editor who had admitted to her unremitting glee, that he had been devoted member of the Mickey Mouse Club as a little boy.

And she wrote so well, best about the huge passions of small people. She wrote about lady wrestlers and first love and dieting-as-psychic-journey. She understood Liz Ray. All this capacity for understanding was aimed outward - she loathed the growing introspections of her era - psychoterapy, psychedelics, and so on.

She was the most private of public persons, and most public of private ones. She lived as if life were not mission or dilemma, but an art. She liked fall clothes more than summer clothes, so she wore them all summer, even in Washington. Since no one could persuade her she was totally wrong in thinking her figure lacked merit, she wore cut-off jeans as part of her bathing suit.

Once, in mulling the publishing of a gallery of accounts of close brushes with death, she told of one she'd had, years before, over the Caribbean in a light plane. One listener recalled it as the only time he has ever heard Marion Clark tell a story twice.

She once needled an over-serious colleague with the phrase: "Everything is style, not substance."

She is survived by her mother, Ada Clark, of Grosse Pointe, Mich., and a sister, Mrs. Fred Aengst, of Corona del Mar, Calif.