Frank Johnson, his hypertension in check, was given medical clearance to resume playing basketball yesterday and a few hours later signed a contract that was slightly modified from the one he had agreed to last week.

Johnson, the team's No. 1 draft choice from Wake Forest, had agreed in principle to a five-year, $200,000-a-year contract with the first four years guaranteed, but the hypertension was discovered in a routine physical examination before the signing of the contract.

Dr. Herbert Singer, the Bullets' internist, immediately put Johnson on medication and began monitoring his progress. After an examination in Singer's office at 9:30 a.m. yesterday, Johnson was given permission to begin practice.

He met Bullet General Manager Bob Ferry at Fort Meade, signed his contract in the bleachers at noon and practiced with the team at 1 o'clock.

"Basically, it's the same contract we had agreed to before all this happened," Ferry said. "We just felt we had to protect ourselves a little more, that's all."

Bill Pollak, Johnson's attorney, agreed that the changes were minor and that four years of the contract still were guaranteed. Neither side would say what the changes were, but they are believed to pertain to Johnson's physical condition.

Johnson said he probably will have to take medication for the rest of his life, "but that's a small price to pay to be healthy. I've been assured that it is under control and it'll stay that way," he said.

Johnson appeared to have little difficulty picking things up in the two-hour practice, but admitted later that he was tired. "He (Coach Gene Shue) showed me no mercy. I was a little winded, but I was pleased."

Johnson said he felt no discomfort because of the hypertension or side effects from the medication.

"He picked things up pretty quickly," Shue said, "but we did keep things pretty basic and he does have a lot to make up. I roomed him with Brad Holland and they'll talk a lot tonight and I'll go over some things with him tomorrow (Saturday) and he'll play in the intrasquad game."

The intrasquad game, scheduled for 2 p.m. today at Dunbar High School in Washington, is free to the public.

The only Bullets who won't play are Kevin Grevey and Jeff Ruland. Grevey dislocated the little finger on his left (shooting) hand at his first practice Thursday and Ruland spained his left ankle last week.

Grevey was fitted with a splint and went through most of the drills with the team yesterday, but won't do any scrimmaging for a few more days.

Ruland is expected to start practicing again Monday.