I'm sure someone who knows more about Clen in particular will chime in, but my question would be: why are you looking to do Clen right now? The general rule of thumb is that controlled substances are only valuable for the last 3% of any results. Diet is 70-80% and training 20-30%. All drugs have side-effects and some sides can be permanent and devastating.
Can a macro split of 50/30/20 be effective? Yes, in general, with a clean diet and correct calories for your size, body fat percentage and goals (ie. cutting/maint./bulking) and provided you are not carb sensitive (more unusual than people think).
I know I sound like a broken record, but I recommend Tom Venuto's Burn the Fat, Feed the Muscle e-book for full, easy to understand information on diet, cardio and weights, all in one place. Once you've done all you can the natural way, look for supplements to advance you beyond your genetic potential - but not until then!
Good luck!