The verbs clean and cleanse share the definition to remove dirt or filth from. But clean is more often used literally. For example, you clean the floor, the dishes, and your hair. Cleanse, meanwhile, is more often figurative. For example, you might cleanse your soul by confessing your sins, or you might cleanse yourself of a bad memory by replacing it with good ones.
Cleanse has two other meanings it does not share with clean: (1) to remove a group of people from an area, and (2) to rid one’s body or a part of one’s body of toxins and other impurities. Definition two, which comes from alternative medicine, is a literalization of the spiritual sense of cleanse. Cleanse in the first sense is often an overpolite euphemism in reference to genocide, but we won’t go into that decorum issue here.
Cleanse predates the use of clean as a verb by many centuries. The earliest documented instances of cleanse in the make clean sense are from Old English—well before the year 1000 AD—and its figurative sense is just as old, so the word has remained more or less unchanged for well over a millennium.1 Clean, meanwhile, is approximately as old, but it was exclusively an adjective for most of its history. It was not used as a verb until around the 17th century, when it gradually began to take the place of cleanse in most of the latter’s senses.2
Clean is literal in each of these sentences:
Pandora emerged from the incident covered in a tar-like substance, and spent part of the afternoon trying to clean herself. [Fairbanks Daily News-Miner]
Dany wins, and Drogo won’t get a septic infection today because the woman will clean his wound. [Wall Street Journal]
Two of the most prominent marble graves in historic East Cemetery have been cleaned of the lichens, moss, mold and mildew soiling them for decades. [Waterbury Republican American]
And cleanse is usually figurative, as in these examples:
It takes all of his cunning to pull off a scam that will free him from their clutches and give Lujan an opportunity to cleanse herself of the demons tormenting her. [Movie City News]
[T]he suggestion that this type of rehab could cleanse him of his sins is disingenuous, at best. [thedailystar.com]
But this is a town full of skeptics, people who buy into all that bricks-and-mortar-and-white-goods fandango instead of having their chakras cleansed. [NPR]