Red clover is a blood cleanser. Chaparral and hydrangea root are better though. For blood cleansing they can be combined for a better effect. Red clover and chaparral are also frequently combined for cancer.
No, allergies to red clover are not common.
By the way, red clover is also helpful for hormones. It contains the same phytoestrogens as found in soy, plus two others.
To cleanse the liver I would go with bitters. For people who cannot tolerate the bitter taste, they can use bupleurum instead. Bupleurum will cleanse the liver without the requirement of contacting the tongue. So it can be taken in capsules.