It would never be a good idea to start using fat burners when you first come off gear. AAS will help you maintain muscle while in a calorie deficit. The purpose of these drugs is to increase your calorie deficit. T3 especially, will burn off fat and muscle. Even with AAS, a good dose of T3 can burn off a large amount of muscle. Increasing thyroid while going into PCT, when your hormone levels are at an all time low could spell disaster! 

In PCT, I would focus on getting enough high quality protein to maintain your muscle and take a few wks to not push the diet quite as hard. Then, once you have recovered and your hormones have returned to normal, clen could be an option to help with more fat loss, on or off cycle. But I would strongly suggest to hold off on T3 until you are on your next cycle.