A potentially critical snag has developed in the Carter administration's effort to reach an accommodation with the textile industry and thereby smooth the passage of a new world trade pact through Congress.

Officials said President Carter signaled his willingness Tuesday night to approve a package of concessions to the textile industry, including tighter restrictions on imports, but first he wants a number of points, raised primarily by the State Department, cleared up.

"We think we have something, but, then again, the whole thing could blow up in our faces," said one well-placed administration official.

Talks are scheduled today involving U.S. Special Trade Representative Robert S. Strauss, Undersecretary of State Richard Cooper, management and labor officials from the textile industry and others in an attempt to "clarify some of the ambiguities," as one official put it.

This means trying to define some key words and phrases more specifically, such as how much is "substantial" when applied to import increases that are to be contained. The offical acknowledged that such an exercise is fraught with opportunities for disagreement.

"He [Carter] didn't want any loose ends flying around," a trade official said.

Carter's failure to give final approval to the textile agreement before leaving early yesterday for a three-day trip to Mexico meant that the House Ways and Means trade subcommittee had to put off action on a key piece of legislation. The bill is believed to hold the key to wrapping up the new trade pact.

The bill would waive penalty (countervailing) duties on imports that have been subsidized by foreign governments. European and other governments are insisting on assurances that the waiver which expired last month, will be renewed, and Strauss has warned that the talks will collapse if the bill fails.

However, the textile industry is sufficiently powerful in Congress that it can, in effect, hold the waiver bill as hostage to its demands for import concessions.

Last year the industry demonstrated its clout by winning congressional approval of an amendment to exclude textiles from any tariff cuts in Geneva. That would also have rattled the negotiating tables but for a presidential veto. Legislation to extend the penalty duty waiver also died. Now the textile tariff exemption has been reintroduced and it hangs like a sword over the trade subcommittee because it could conceivably be tacked onto the waiver bill.

Rep. Charles A. Vanik (D-Ohio), chairman of the subcommittee, served notice yesterday that -- in light of last year's travails -- the subcommittee will not act on the waiver without an agreement satisfactory to the textile industry.

Vanik called the White House delay "regrettable" but aides said later that the subcommittee is prepared to act as soon as an agreement is in hand.

Rep. Kenneth L. Holland (D-S.C.), a leader of the textile protection effort on the subcommittee, told a reporter he thinks industry would be satisfied with the agreement, based on known details of it. But he said he thought the waiver bill would be defeated on the House floor if the textile industry agreement is not consummated.

The accord with the White House envisions further cutbacks in recently renegotiated quotas for textile imports as well as export promotion and domestic productivity incentives.