Sen. Dick Clark (D-Iowa), who is emerging as a principal advocate of new arms control agreements with the Soviet Union, said yesterday that arms control advocates have nothing to be ashamed of and should take on the "hawks" more forcefully.

Speaking to a meeting of the Arms Control Association, Clark said arms controllers too often let hard-liners establish the terms of national security debates. Referring specifically to the Strategic Arms Limited Talks (SALT) agreements now taking shape in engotiations in Geneva, Clark said a stronger case could be made for them than has been made thus far.

Earlier, Clark told United Press International that Secretary of State Cyrus R. Vance had personally urged him to devote more time to mastering complex SALT issues to prepare for next year's anticipated Senate debate on the new agreements.

His subsequent speech suggested that Clark has begun to take this advice.

"As a member of the Senate Foreign Relations Committee," Clark said, "I am not prepared to stand aside and allow the terms of this debate to be determined by those more vocal than myself."

"We must reject the implication that arms control is less tough-minded than the critics' view,' Clark said. "Ours is the realistic and the practical view."

He gave a detailed defense of the major portions of the new SALT agreements, details of which have appeared in leaked news accounts, and said a crucial issue is what would happen if the Senate rejected a new SALT package.

Clark predicted a new arms race "more furious than we have seen to date," a deterioration in overall Soviet-American relations and an increased "mathematical probability of nuclear war" if the Senate rejects the pacts.

Clark said the new agreements would force the Soviets to give up about 300 intercontinental strategic weapons that is now has aimed at the United States, would provide for numerically balanced forces on both sides, and would enhance U.S. security.

The critics' technical arguments suggesting that the Soviet Union might try to wipe out America's land-based missile forces in some future crisis avoids the question of whether Soviet leaders could conceivably want to take that risk. Clark said.

To suggest seriously that they would try to wipe out U.S. land-based rockets "is to enter the realm of mystic philosophy," Clark said.