A lot of clothes aren't particularly practical. I'd argue that artifacts are more likely to be art if their purpose is more aesthetic than practical. As such, I'd say that some articles of clothing are art (like anything you see on a runway), some aren't (e.g. basic T-shirt), and some seem ambiguous to me (some ties might be art, but some are pretty boring and they don't have much practical use).

I have a very nice knife that is absolutely art, and is extremely useful.