National security adviser William Clark and former secretary of state Alexander Haig stood engrossed in serious conversation next to a spitting fountain last night. They kept mumbling something about "the president" and "keeping the lid on it."

But they were speaking too low for effective eavesdropping. And no--Al Haig said he had absolutely zilch advice for the president on the current Central American crisis.

"I don't believe in giving advice to a president for whom I no longer work," said Haig, looking tan and fit at the first annual Children's Ball for Cystic Fibrosis. "I want George Shultz and the president to work it out . . . The last thing they need is a nitpicking outside expert."

Haig, working the tony party at the Organization of American States as if he was still secretary of state, said he hasn't "been reading many books, just writing one." No surprises in the historical manuscript due out next spring, he said. "Just the truth and that's a rarity in this climate."

"AAAL! Howareya? How's the tennis game?" cried former transportation secretary Brock Adams.

"Getting better all the time, Brock!" said Haig.

"You look well," expounded Adams.

"I'm feeling well," said Haig.

"Great!"

That was the end of that conversation.

Across the fountain were Treasury Secretary Donald Regan, Commerce Secretary Malcolm Baldrige and others talking about--what else--the economy. And suntans.

"No, I didn't get this at Williamsburg," said Regan, slightly pink faced. "I worked there. I sneaked out today over to Burning Tree and hit a few balls. You know, the boss is out of town at Camp David so I could . . . "

Among others there for the white gazpacho and veal were Interior Secretary James Watt, Sen. John Warner (R-Va.), former presidential aide Lyn Nofziger, and U.S. trade representative Bill Brock.

An unusually impressive crowd for a first-time event--about 300 of Washington's power elite--gathered amid the marble and shrubbery of the OAS building. In Washington, all it takes for a successful fundraiser is a chairperson with a name. In this case, it was Joan Clark, wife of the national security adviser.

Tables went for $5,000 and more than $100,000 was raised for cystic fibrosis, a lung and digestive tract disease in children that is always fatal.

"You know we're not cancer or heart--we're cystic fibrosis--so this is very exciting for us," said Bob Dresing, national CF president. "We wanted a very important person as chairman to attract just the right kind of people for the ball."

The $100,000 will be used to launch the Nancy Reagan Cystic Fibrosis Research Fund at the University of California at San Francisco. It will be headed by Dr. Jay Nadal.

"I'm here because of the money and because Reagan is from California," said Nadal, a nationally renowned CF scientist, who described himself as a Republican but "not this kind of Republican.

"This is also great for visibility. It's really not the money. We get million-dollar endowments. But it's important for people to know. We're not making any promises . . . We're just going to try . . . "