T3 and Clen are not fat burners, they are compounds that increase BMR. They're use in cutting is to raise your caloric maintenance threshold so you don't have to diet as hard and to keep your metabolism from slowing down to badly as dieting goes on.

It's simple, calories in > calories out = anabolic (tissue building), and calories in < calories out = catabolic (tissue breakdown). So you're goal in PCT is to try to stay in that anabolic state so that you don't waste too much of your new muscle, so if you're using these compounds or not, the equation stays the same. If you would like to limit the amount of fat you put on, it will be up to diet, with a little bit of help coming from specifically timed cardio.

I would stay above your caloric threshold if you would like to keep as much of the new muscle as you can, but that means no matter what you will gain some fat. You can slow it down and keep it very minimal through the means that I've mentioned.