Former Defense Secretary Clark M. Clifford, who has advised every Democratic President since Harry S. Truman, will visit Greece, Turkey and Cyprus later this month to make an independent assessment for President Carter of how the United States might help bring peace to the divided Meditteranean island.

In announcement the trip yesterday, White House press secretary Jody Powell said Clifford will serve as Carter's personal emissary without formal diplomatic rank."

His trip will be the fourth such fact-finding tour abroad ordered by Carter and was announced one week after the first meeting in 13 years between President Makarios, a Greek Cypriot, and Rauf Denktash, the leader of the Turkish Cypriots.

Powell also announced yesterday that:

Carter "deplores" an ethnic slur made against Ralph Nader by Federal Trade Commissioner Paul Rand Dixon.

Legislation authorizing Carter to carry out his often-promised reorganization of the federal government will go to Capitol Hill today.

Telephone calls and telegrams reacting to Wednesday night's "fireside chat" by the President were overwhelmingly favorable.

The White House may make its own investigation of whether natural gas shortages are real or contrived.

The President will not fire civil servants to bring federal employment in line with whatever ceilings he decides to set, but will rely on attrition and leaving vacancies unfilled.

Powell said a timetable has yet to be worked out on Clifford's trip, but he will be in Cyprus in mid-February, and will also consult with U.N. Secretary General Kurt Waldheim as well as leaders of the European Economic Community.

Clifford, now a Washington attorney, was a White House counsel to Truman, and helped formulate the 1947 "Truman Doctrine," which extended American aid to Greece and Turkey.

After saying Tuesday that Carter expressed no reaction to the FTC's Dixon's characterization of Nader as a "dirty Arab" and a "son of a bitch," Powell said yesterday that Carter "obviously deplores this or any other racial or ethnic slur."

Powell also said the FTC is an independent agency, and Carter has no power to call for Dixon's resignation.

Asked whether U.N. Ambassador Andrew Young still believes that Cuban troops "bring a certain stability and order" to Angola, now that the State Department has said neither it nor he condones their presence there, Powell first said, with a smile:

"I think you can assume that he agrees . . ." with the State Department. Then Powell added, "I think it is certainly possible to deplore a circumstance that may in fact be stabilizing."

After reporting that in the wake of Wednesday night's "fireside chat" the White House received 487 favorable telephone calls and telegrams, and only 55 unfavorable, Powell was asked if any of the favorable response had been organized.

He answered with the humor that has become a trademark of his daily briefings: "All I know is a week ago we sent Miss Lillian six pounds of dimes."

Carter "seemed to be generally satisfied with the reaction, both from the public and from individuals," Powell said.