Saying that he was "overly cautious last week," a better-coached Kenneth L. Adelman returned to the Senate Foreign Relations Committee yesterday with crisper answers in hopes of reviving his nomination as director of the embattled Arms Control and Disarmament Agency.

Last Thursday, Adelman, 36, the deputy U.S. ambassador to the United Nations, ran into trouble in answering basic questions about arms control. Many members of both parties found his responses vague and sometimes evasive and were left with doubts that he could handle the job.

In the past seven days, however, the White House pulled together a new backup team for the nominee and moved to reassure doubting committee members about both him and the administration's commitment to arms control generally.

When four more hours of testimony concluded yesterday, Adelman's chances for approval by the 17-member committee appeared bright, according to Powell Moore, assistant secretary of state for congressional affairs, who attended the session.

Six of the eight Democrats on the committee tentatively decided earlier this week to vote against Adelman. A seventh, Joseph R. Biden Jr. (Del.), is wavering. The eighth, Edward Zorinsky (Neb.), is for him.

Three of the nine Republicans were also described earlier as wavering: Charles McC. Mathias Jr. (Md.), Rudy Boschwitz (Minn.) and Larry Pressler (S.D.).

Boschwitz said last night he had now decided to vote in favor of Adelman. "He made a comeback," Boschwitz said.

Pressler, however, said last night, "You can say I'm leaning against." He said his main reason was Adelman's apparently negative attitude toward a pending test ban treaty with the Soviet Union and the possible resumption of talks on an anti-satellite pact. Pressler said both had been supported by Eugene V. Rostow, the fired ACDA director.

Mathias was unavailable.

A fourth GOP member appeared to join the undecided list yesterday. Sen. Nancy Landon Kassebaum (R-Kan.) told reporters during a noon break that she had not made up her mind. At the afternoon session, she told Adelman three times that she was "disappointed" by his testimony both last week and yesterday.

As the session ended, Chairman Charles H. Percy (R-Ill.) announced that the committee would vote on the nomination Feb. 15. He, too, had inquired earlier about the two pending treaties. He announced the scheduled vote after Adelman told him yesterday that the administration would decide its next step on both by Feb. 14, when Congress is to return from a coming recess.

At the same time, Percy disclosed that another potential problem for the nomination had been removed; a scheduled session with Rostow will not be held until April. Democrats wanted to use that session to explore the president's arms control policies before a vote on Adelman.

White House concern over the nomination was apparent yesterday in several ways. For one, Tom C. Korologos, a veteran congressional liaison man from the Nixon and Ford administrations, was on the scene--brought in, he said, to help Adelman.

Adelman also acknowledged that in recent days he had undergone two so-called "murder boards"--preparatory sessions at which administration officials play the part of inquiring senators.

Last week, when asked about limited nuclear war, Adelman said he had "no thoughts in that area." Yesterday he said a nuclear war could not be limited.

At the earlier session, he refused to say whether one side could prevail in a nuclear exchange; yesterday he conceded that neither side could.

Last week, he responded that he "never in my life" contemplated how he would deal with a verified Soviet offer to do away with all nuclear weapons. Yesterday he said he was thinking that it meant a bilateral treaty and he had been confused because he knew it would leave other countries with nuclear weapons.

Sen. Paul S. Sarbanes (D-Md.) led Adelman through a series of questions on Rostow. Adelman said Rostow was "gifted" and had "performed very well," and he had "not sought to ascertain" why Rostow had been fired.

Adelman added that "it would not be useful for this committee to go into" the Rostow firing.

The Foreign Relations Committee helped create the arms agency, one objective being that the director balance against the Pentagon on arms control.

In another action, the committee approved by a 9-to-1 vote and sent to the floor the nomination of Richard R. Burt to be assistant secretary of state for European affairs. The only no vote came from Sen. Jesse Helms (R-N.C.), who along with several other conservative senators had held the Burt nomination up for almost six months.