I would have thought this is a good definition: 'A nubile young temptress, who dresses teasingly and provocatively.' Some definitions that I looked up were a bit extreme for the word 'tart.' I can't help but think sexist terms to describe women, such as slut, whore etc, with no similar words to describe men are derogatory to women. I avoid using them, but would have thought tart was not in the same boat.
I have mentioned on GN before that I brought my children up to not use words that put women down. It was never okay in our home to use belittling words to describe women.