Deputy Secretary of State William P. Clark will visit South Africa, Namibia and possibly Zimbabwe next week to explore practical ways of winning an internationaly acceptable agreement on Namibian independence, Reagan administration sources said yesterday.

The sources said Clark's trip does not signal a basic change in the administration's high-priority goal of trying to use a solution to the Namibia conflict as a bridge to improving U.S. ties with South Africa and combating Soviet influence in southern Africa.

Instead, the sources added, Secretary of State Alexander M. Haigh Jr. feels that the dispatch of Clark, the highest-ranking U.S. official to visit Pretoria in some time, will underscore the importance that the administration attaches to pursuing closer relations with the South Africans while reassuring black Africa that Washington has not abandoned its interests.

The administration's pursuit of this goal has been thrown into disarray by failure to achieve agreement on Namibia during the recent visit here of South African Foreign Minister Roelof (Pik) Botha, the subsequent leaking of State Department documents related to Botha's visit and evidence of unhappiness in the administration and conservative congressional circles with the performance of Chester A. Crocker, assistant secretary of state-designate for African affairs.

Senate Majority Leader Howard H. Baker Jr. (R-Tenn.) announced yesterday that Crocker's principal Senate critic, Jesse A. Helms (R-N.C.), has removed the hold he had placed on Crocker's nomination.

Haig is known to have been angered greatly by the leaks, which indicated U.S. willingness to help South Africa's white-minority government end its international isolation if it cooperates in giving independence to Namibia, a predominantly black territory it has controlled since the end of World War I.

An investigation of the leaks is under way, spurring speculation that Crocker's tenure may not be secure. In addition, there is a feeling among has congressional critics and some senior administration officials that an African visit by Crocker earlier this year antagonized the South Africans and black Africans.

For that reason, the sources said, Haig decided that a fresh approach by a very senior official might help. Although Clark is a newcomer to foreign policy who was unable to identify the prime ministers of South Africa or Zimbabwe during his confirmation hearings, he has been increasing his authority and influence with Haig.

The sources said Botha, during his visit here, agreed to a visit by Clark. According to the sources, Botha and Haig felt that Clark's 12 years as a California state supreme court justice might help unravel some complex legal issues in the Namibia dispute.