This relates to some earlier comments.
Attempts at definition, be they of art or love or friendship, all ultimately seem to flounder and fail. We can say what they are not in a large number of cases and provide examples which show this as clearly distinct (although this may be harder in the case of art than any other) but providing a complete definition seems to fail on the use of the word, i.e. it is too well used, or perhaps, we could say it is used too often in situations were it should not and instead merely gestures towards a 'something like...'
However, the fact that this 'gesture' is understood at all shows that there is something being communicated.
What then does art communicate? That here there is something of value.