Credit clearing is the practice according to which a small group of banks need to make many payments to each other, of adding up the payments and cancelling them out before settling the remainder.
This process originated between all the banks in London, who would send their checks to the clearing house at the end of each day.
After the calculations were made there would be a single payment to or from each bank.
In 21st century with spreadsheets and blockchains, this process tends to be fully automated.
Many complementary currencies work this way, calling it mutual credit.