I want to say, I have a type of hair that grows fast like:
My hair is a fast-growing.
where fast-growing is an adjective and the article "a" connect the adjective "fast-growing" with the noun "hair". Is that correct usage?
It is not a correct usage to say: My hair is a fast-growing because articles must be followed by nouns either with or without adjectives in between.
You can say I have fast-growing hair
or My hair grows fast/My hair is growing fast
or just My hair is fast-growing
All of the alternatives above don't use the article a because the noun hair refers to the entire strands of hair on your head.
Let me know if you ever come across this kind of sentence.