First, put a villager to extract pulp from the vines north of the granary. You would need cutting tools for this. Then, get salt water and cook the concoction. The villager will spread the extract to a flat rock southeast of the granary. Put villagers to the yellowish colloid until the cloth is made to 100%.

A lot of cloth is made from plant fibers (cotton from cotton, linen from flax, burlap from hemp, etc). Try dropping a villager on various non-food plant materials - as long as you've got cutting tools the villagers should go grab one and start harvesting.

Follow where the villager takes the harvested plant life and you should figure out step two (tip: salt water).

Since that step is the equivalent of separating the fibers out in the real world, the next step would logically be to compress the fibers back together as cloth. The villagers don't seem to have a loom, but there's another plant product that could serve as inspiration. In fact, you might be writing these hints down on it right now!

re-put your villagers on the pulp on the stone. Several time and several villagers, its a big work!

Okay, so you need Lvl. 2 Science to get the clothing hut, right?