Clen was anabolic in rats who have an abundance of beta 3 receptors (in doses that would proably kill us). Beta 3 receptors in animals help with insulin secretion and sensitivity. Humans barely have any (if any at all) therefore as size said, its not that anabolic. Clenbuterol will also cause a drop in thyroid production, hence then reason people add T3 to their fat loss stack. Using this combo for any other reason is pointless.
T3 causes a cascade of effects which promotes fat and muscle loss if calories are not above maintenance. You can take all the protein you want but the glycogen inhibition, insulin blunting and cortisol stimulation effects of T3 will eventually cause muscle loss. Gluconeogenisis will be increased drastically while on T3 no matter how much protein you consume. Eventually, muscle loss will occur. The only way to counter these effects is with some sort of anabolic and clen will NOT do it.
And I've used T3 for very long peroids of time in varying doses (bulking and cutting cycles)