You are right that 'clothes' is always plural. Clothing is always uncountable. It has no plural form, and cannot be used with an article. You can say 'waterproof clothing' without an article, and you can use 'some' with 'clothing'. For example; 'Students must bring waterproof clothing on the trip'. If you really want to use the article 'a' here, you would have to say 'a waterproof coat' for example, or if you want to be more general about the type of clothing, you could say 'a waterproof garment'. 'Garment' is the only word in this semantic group - with the general meaning of 'clothing' - which is a countable word with a singular form. Yes ,'cloth' is a synonym of material or fabric, and is usually uncountable. It's just about possible to say 'that's a nice cloth' or 'the designer showed me some different cloths', but it sounds a little strange. We'd be more likely to say 'a type of cloth' (singular) or 'types of cloth' (plural).

встречалось: civilian / equestrian clothing his ordinary pesonal tastes in clothing and food he has spots of paint all over his clothing patterns for women's / men's and boys' clothing to mix the concrete, wear safety glasses, a dust mask and old ot protective clothing he donned the protective clothing, face masks and oxygen bottles a chain of clothing stores a vintage clothing store your clothing and appearance is one of the first things noticed about you I'm going to buy some new sommer clothes designer clothes and accessories second-hand clothes he changed into civilian clothes her clothes were ragged and unwashed the mysterious man in rumpled clothes

Clothing is more like an adjective. -A clothing line -Some clothing items -A clothing chain -A waterproof clothing item Cloth is a quantifiable entity and can be both singular and plural, clothing is to attribute something to clothes (for instance ideas for clothing).