This is nothing more than a complete skirt with a bodice attached at the front of the skirt and zippered or buttoned down the back. The piece, when worn, would cover everything you want, but not the horse portion of the Centaur.
BTW, if what you're thinking is, "you know, that's really nothing more than today's backless dress...," you're on the right track.
Your real problem is, "can a centaur wear a skirt?"
The answer in this case is "no." The skirt, by itself with no other support, would have nothing to hold onto as it "waist" of the skirt could be no higher than the "chest" of the horse. It would be like people wearing skirts (or pants) no higher than their crotches. I guess if you tie the belt tight enough, but if you think that's practical, I want' you to consider the meaning of the word "mince" when used to describe walking.
Which means you have a general conclusion that is, conveniently, genderless
What this means is that a Centaur really can't wear anything... not a pair of shorts, not a pair of pants, not a skirt, not a dress... nothing... unless it's attached to the "top part" (bodice) of the clothing. Centaurs can't wear pants (or skirts, etc.) without something to hold them up. And that something really has only one practical expression:
Whether an attached bodice or suspenders worn beneath a shirt, it makes no difference.