This is Wistful Tinker, or just Tink.

Tink is a magic student. Not a special pupil like Twilight was, but she is a teacher at Celestia's school(in my headcanon XD) Her magical ability is to manipulate the four material elements(earth, water, fire, air). Her magic gives her control over them like how the Benders in Avatar: The Last Airbender use the various elements

just a quick full body ref, both filly and adult used GeneralZoi's ponymaker on Deviant art