It's "clothes are". The word clothes is always used in a plural form and takes a plural form of a verb.
It's "clothes are". The noun "clothes" only has a plural form and takes a plural form of a verb.
Are your clothes clean?
Is your clothes clean?
Follow the same rule with other verbs to say, for example, "Your clothes look great." (not "looks great."), "clothes hang..." (not "clothes hangs..."), or "clothes have..." (not "clothes has...")
Some of my woolen clothes have a stain.
Some of my woolen clothes has a stain.
We also use a plural determiner (these, those, etc.) or pronoun (they, them, these, etc.) to identify or replace this noun.
Are those clothes yours?
These are my clothes. They are on the floor.
Be aware that we cannot use the article a with "clothes" because "a" is for one. However, when talking about a single item, you can use the following expressions:
- a piece of clothing
- an article of clothing
- an item of clothing
- a garment
Did you buy a new piece of clothing yesterday?
All of them are correct and well-accepted, but the most popular choice in everyday English is naming the specific piece of clothing.
My T-shirt is in the drawer.
A partial list of pieces of clothing that only have a plural form, and therefore take "are" (not "is"), can be found below: