Is this sentense gramatically correct?

[shalibo]

Is this sentense gramatically correct and could it be applied in formal written English?
I want to buy the same clothes, the old one of which is worn-out.
Actually, this comes from two sentenses:
I want to buy the same clothes. The old one is worn-out.
Thank you for your answer.

[Alan]

Unfortunately, this sentence does not work because of 'clothes' being an uncountable plural noun (meaning that you cannot say *'one of the clothes'). You would need to rephrase the relative clause, albeit cumbersomely, to e.g.'... among which one item is worn out'.