Yohimbine is an alpha receptor antagonist. Alpha receptors reduce fat burning, so when you combine a alpha receptor antagonist (yohimbine) with a beta receptor agonist (clenbuterol), you’ve just created a powerful chemical environment for burning fat.
You could take supplements to counteract side effects, however if you take away the stimulative effect then you also take away the fat-burning effects they’ll have on your metabolism. One supplement I recommend to keep your blood pressure under control however is hawthorn. This won’t calm your nervous system and reduce thermogenesis but it will keep your BP from going too high.
To minimize side effects, you can run short cycles that only last 2 weeks at a time. After this duration the risk of developing more severe side effects increases. Also clenbuterol’s effectiveness reduces after 2 weeks anyway, so there wouldn’t be much sense in running longer cycles as it wouldn’t give you any more fat loss.