NANCY REAGAN in Jackie Kennedy's house?

Not the White House. Wexford, the house former First Lady Jacqueline Kennedy Onassis designed and built herself in the Virginia Hunt Country.

Now owned by conservative Republican Gov. William P. Clements Jr. of Texas, the 46-acre estate is being touted down in Middleburg as number one on a list of suitable temporary residences for the house-hunting Ronald Reagans.

Reagan, who is moving his campaign headquarters from Los Angeles to Arlington, Va., sometime in August is also looking for a house here.

The beautifully-furnished Wexford, which is vacant except for a caretaker, seems perfect to those who have been touting it. There is a pool, a pond, a tennis court, stables and all the open spaces of fox hunting country for the horse loving Reagans to explore.

There is also ready-made space for the Secret Service. When the Kennedys built the place, the government put in a bomb shelter with living quarters above ground for security guards. The structure is now a guest house with a bedroom, kitchen, living room, bath and laundry.

Clements' wife, Rita, a former Texas Republican committeewoman, said last week that there has been a lot of telephoning about the house but "nothing is decided yet."

"It's a personal decision between us and the Reagans," she said. "There are no real estate agents involved."

She and the governor are coming up next week to look things over.

Spectacularly landscaped, the house is filled with 17th and 18th century antiques, "mostly English."

Many Republicans, including George Bush, have been entertained there in the past. But the Reagans haven't seen it yet.

Clements, who bought Wexford when he was Deputy Secretary of Defense, makes no secret of hoping to come back to Washington.

Although vocal in his dedication to President Carter's defeat in November, he withheld his support in the primaries while two of his close friends -- John Connally and George Bush -- were still in the race.

Clements, although not high up on the list, is one of the 18 under consideration by Reagan as a possible running mate.

Unless he knows something the rest of us don't, time is getting short for former Vice President Spiro T. Agnew if he wants to start drawing a $15,625 a year government pension next November.

Agnew still needs three more months on the federal payroll to have completed the five years necessary for him to qualify.

Agnew's pension has been a puzzlement to some in the federal bureaucracy since he resigned on Oct. 10, 1973.

Agnew was covered by the Congressional Retirement System. He had paid 8 per cent of his $62,500 annual salary, or $25,000, into the pension fund.

Instead of withdrawing his contribution when he resigned, he left the $25,000 there, drawing no interest, and presumably doing him no good unless he planned to return to government at some time.

He needed money badly and has said he had to borrow $200,000 from Frank Sinatra to survive.

Nevertheless, he never touched the $25,000. It is still there.

Now, he will be 62 in six months. He needs to work for Uncle Sam in some capacity for three of those months to become eligible for monthly retirement checks.

When California Democrat John Moss was still in Congress, he had his staff watching Agnew's pension account to try and figure out what he had in mind.

There was suspicion that Agnew might serve his extra three months on a payroll buried so deep in the federal bureaucracy that it couldn't be traced by anyone who didn't already know where to go to look for the records.

All Agnew needed, Moss's aides discovered, was a friend in the government who would put him on the payroll in some obscure, low-paying job such as a fisheries commission in Nome, Alaska, just long enough to qualify.