There was a time when Tandy Cronyn was so tired of casting agents and directors asking her if she was in fact the daughter of Hume Cronyn and Jessica Tandy that she got mischievous.

"No, I'm the daughter of Anne Jackson and Eli Wallach," she told a few of them.

Cronyn, appearing currently at the Olney Theatre as the daughter of aging parents in "Painting Churches," knew when she was 12 that she wanted to be an actress. She was not dissuaded by her parents, who asked that she go to college first.

"I didn't really want to, so I made sure I flunked so badly I could leave after one year," she said.

Her brief stay at McGill University was followed by one at the Central School of Speech and Drama in London, the school famous for producing, among others, Laurence Olivier and Peggy Ashcroft. She didn't finish that either. "Three years seemed too long," she said.

Before that was a fashionable high school in New York, The Brearley School, interrupted by two years in a German boarding school to learn German. She is currently spending her off hours brushing up on that language because it could lead to a film role.

Cronyn, who has never acted with either of her parents and doesn't want to, has performed in many resident theaters over the past 15 years or so, playing classical roles such as Ce'lime ne in "The Misanthrope" and Hypatia in "Misalliance." She's done Sally Bowles in "Cabaret" and Amy in "Company" (which played here at the National). But she finds herself on a plateau at this point in her career, considered primarily a stage actress and a little frustrated by her inability to break through to the visibility offered by film and television.

"You can't make a living anymore just doing theater," she said. "So every now and then I pack my suitcase and go to L.A. and make the rounds."

Recently she got an unusual part, for her, in a television movie. Normally cast as middle- or upper-class women, this time she was given the role of a biker's wife who lived in a slum and had an illegitimate child. She had to fly back to Los Angeles at her own expense for the filming, but was excited about the change of pace, even if it was only one scene. But by the time the star got finished rewriting it, her part was so small that, she said, "if you blink you'll miss me."

That's show biz. "I take what I can get," she said bluntly. "I suffer from being hard to label. In this country there is this huge layer of middlemen, the casting directors and agents, between the actor and the producer, because there's so many actors. And the only way they can cope is to categorize you. But I think it will be the death of the acting profession."

At one point she left acting and worked for three years on the staff of the National Theater of the Deaf, tired of living out of a suitcase and hoping that administrative work would lure her away from acting. It didn't, and she returned to the family profession, doing 11 plays in 2 1/2 years in Denver and San Diego.

Her mother, now in her seventies, has been rediscovered, in a sense, in the last 10 years, newly revered and sought after. Cronyn attributes that to her father, who produced a two-person program they toured in that led to "The Gin Game" and "Foxfire," which he also cowrote. "My father doesn't sit around waiting for the phone to ring," she said. "My mother is more of a well-bred English lady who waits to be asked."

She recalled seeing a foreign-born actor who couldn't speak English being interviewed on a television program. He was asked to define acting, and stood, placed his hands over eyes and mimed jumping off a cliff. "That's it," Cronyn said. "Jumping off a cliff with your eyes closed."