Opus Antiques has dated this piece to the Georgian era.

It measures approx 33cm l x 3.5cm w
Corsets were called stays and a treen stay busk was essentially a flat piece of wood which fitted into a front pocket of the corset. Many were plain but the carved ones were given as love tokens with symbols similar in meaning to the Welsh Love spoons.
For more info on stay busks https://www.opusantiques.co.uk/single-post/2017/10/03/Antique-Treen-Stay-Busks---what-are-they
Opus Antiques has dated this piece to the Georgian era.
Antique treen, boxes & decorative georgian items
You can view the stock and full dealer information on the Opus Antiques Profile Page