I can see that being a style Tonks would wear. That said. That is in all likelyhood not lingerie. It is also more than likely NOT a Bustier. Rather it is a great deal more likely that what she is wearing is what is referred to as a Corset.
The difference between a Corset and a Bustier is that a Bustier is designed primarily to boost a woman's assets, while a Corset is designed to cinch a woman's (or in some cases a mans) defects. Strictly speaking Nymphadora Tonks does not require either of these types of garments due to her Metamorphmagus powers. However taking that into consideration, it is far more reasonable to assume she would wear a Corset (which wouldn't really be a hindrance to her) than it is to assume she would wear a Bustier (which would provide absolutely no benefit to her under any circumstances).
An additional reason for assuming that what the Nymphadora Tonks in this image is wearing is a Corset and not a Bustier is that the Bustier is a Muggle invention that dates back only to the 1950's. Where as the Corset dates back to 2,000 B.C.E. at the absolute earliest. This means that the Purebloods in the Wizarding World of Harry Potter would be a crap ton more accepting of the Corset than they ever would be of the Bustier, due to the length of time that the Corset has been in existence when compared to the Bustier. As such this image should probably be re-tagged so that it is listed under the Corset category instead of the Bustier category. But I would rather not do that myself because the last time I tried to re-tag something this subjective I got yelled at.
