A big jump in clothing prices and still soaring food costs sent inflation up 0.3 percent in September, bringing the annual inflation rate for items other than energy to its highest level in seven years, the Labor Department reported Friday.

The Consumer Price Index, compiled by the Bureau of Labor Statistics, notched up 0.3 percent after adjustment for seasonal variations, on the heels of the 0.4 percent increases in both July and August.New fall fashions sent apparel prices up a sharp 2 percent in September, after dropping 1.6 percent in August, the bureau reported. That matches the large increases in clothing costs reported in March and April.

As for food, the drought was still pushing prices higher. Food and beverages cost 0.8 percent more in September, the steepest jump since a 0.9 percent rise in July and following a 0.5 percent increase in August, the bureau said.

Prices at the grocery store leaped 1 percent in September, about 80 percent of this due to a 4.5 percent jump in the costs of fresh produce. Partially offsetting this shock was a decrease in the costs of meat, poultry, fish and eggs.

Together, the increased costs of food and clothing accounted for more than 70 percent of the rise in the Consumer Price Index, the bureau said.

In contrast, the costs of energy products and school tuition and fees turned down in September, and shelter costs rose less than in August, the bureau said.

The inflation rate for the third quarter of 1988 rose at a 4.8 percent annual rate, compared to the 4.2 percent and 4.5 percent rates of the first and second quarters, the bureau said. This brought the year-to-date annual rate to 4.5 percent, compared with 4.4 percent for all of 1987, the bureau said.

When the costs of energy are excluded, the Consumer Price Index has increased at a 4.8 percent annual rate so far in 1988, its largest advance since 1981, the bureau said.