It seemed a perfect putdown, causing sophisticated Tennesseans to chuckle, when Mayor Randy Tyree persuaded the Knoxville City Council to rename a downtown plaza for a remote town in Alabama.

Tyree's playful resolution designated the area outside the Tennessee Valley Authority's new twin-towers headquarters complex as "Muscle Shoals, Alabama."

Heh, heh, heh, chortled Tennesseans - that will show the federal judge and the uppity Alabamians, especially those in the real Muscle Shoals, several hundred miles from Knoxville.

But Alabama failed to see the humor in Tyree's resolution, and now, far from being a laughing matter, a presidential nomination to the TVA board is caught in a tangle of national and regional politics.

Since February, President Carter's nomination of Robert Clement of Tennessee has been pending before the Senate - hung up, in part, over the Muscle Shoals dispute.

Sen. Howell Heflin of Alabama, a Democrat like Carter and Clement, has staged a one-man assault on the nomination, accusing Clement of "moral turpitude" and a bias against Alabama.

The "bias" is assumed to be Clement's view that TVA headquarters, with its 5,000 employes, should remain in Knoxville instead of moving to Muscle Shoals, as has been ordered by a federal judge.

Earlier this year, in a suit filed by the state of Alabama, the judge held that the TVA Act of 1933 required TVA's principal offices to be located in Muscle Shoals, a town of 7,000 in northern Alabama. TVA has appealed the ruling.

TVA has extensive facilities in Muscle Shoals, but not its principal office. And Clement, a familiar political figure who ran for governor of Tennessee last year, thinks Knoxville is just fine for TVA.

Heflin and the rest of the Alabama congressional delegation, unhappy with that view and fearful that Clement would use the TVA seat as a platform for future office, sought in vain to meet with Carter before he made the nomination last winter.

The flap has gone on since then.

At one hearing, Clement disclosed that Heflin suggested his confirmation would go "smoother" if he promised to "recuse" himself from the Muscle Shoals controversy.

Clement refused. Then Heflin questioned why Clement failed to file his campaign spending reports on time last year (the state attorney general found no ground for prosecution).

Heflin is expected to probe further into that subject at Senate Environment and public Works Committee hearings today.

The committee is expected to decide today whether to confirm or delay Clement's nomination to the partial term, which expires in 1981.

The Heflin-Clement squabble reflects a larger amount of pushing and shoving among members of Congress from the seven-state TVA region, with even the Democrats in uncustomary disarray.

Historically, Democrats and Republicans have tended to stand shoulder-to-shoulder on TVA issues. The TVA has transformed the valley, providing flood control, cheap electricity and resource and industrial development.

The Heflin-Clement dispute is only a part of the unraveling of the unity. Other recent infighting has included:

- Rep. Tom Bevill (D-Ala.) in a key Appropriations Committee spot, has rankled other TVA-state legislators by insisting that TVA locate a synthetic fuels plant in Alabama. Sen. Jim Sasser (D-Tenn.) opposes the idea and is trying to get the government to locate a plant in Tennessee.

- Sen. Wendell H. Ford (D-Ky.) first held up a bill to raise TVA's debt ceiling, then tried unsuccessfully to amend it by expanding the TVA board from three to five members, with one seat assured for Kentucky.

The committee may settle the Clement issue this week, but there will be more sparks in Congress over TVA.

Sasser and Sen. Howard H. Baker Jr. (R-Tenn.) have introduced a bill to ban the move of TVA to Muscle Shoals. Alabamians, of course oppose the bill.