Having the shape of Rubik's puzzle (5)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
cubic
(Other definitions for cubic that I've seen before include "With six sides - raised to the third power (maths)" , "Three-dimensional" , "(Of a solid) square-sided" , "Equation to the third power" , "Equation involving third powers" .)