03/26/2014 09:06 am ET Updated Mar 26, 2014

Selena Gomez Slips Into Sheer, Backless Shirt For Sultry Instagram Photo

What's the big secret?

Selena Gomez looked all dolled up in a sheer, backless top and black shorts while on set Tuesday, March 25. She uploaded a flirty photo to Instagram and teased fans. "... Secret project," she wrote. While it's unclear what the 21-year-old is working on, she did offer a look behind-the-scenes as she posed in a vanity mirror.

Us Weekly noted that it appears the "Come & Get It" singer is getting back to work after a hiatus. She canceled part of her Stars Dance Tour in December and allegedly headed to rehab in January for "emotional issues" and "partying."

This latest pic comes after Gomez shared a seemingly "nude" photo showing her tangled up in some airy curtains just last week.