clothes

[Viketoliia]

He avoids of buying (an) expensive clothes. Нужно (an)?? clothes это ед число или множ???

[garyg]

Either "he avoids buying expensive clothes" or "...expensive clothing". There's no need for an "an".

If for some reason you wanted to use this article in a sentence you could write or say "he avoids buying an expensive item of clothing" but it'd sound a bit odd to use "an" instead of, for example, "any".