Clen is very anti-catabolic so you don't have to worry about losing gains IMO. T3 on the other hand, from what I understand, need to be not overdone. But that could be broscience for all I know. Just what I've read & heard.
I used Clen off and on, and T3 only a handful of times during a Test+Dbol cycle with good recomp results. Definitely throw in Clen I'd say.