What did the 22nd amendment clarify?
who was the cause of this amendment?

The Twenty-Second Amendment, ratified in 1951, limits presidential tenure: no person may be elected President more than twice. This section clarifies original constitutional language on the status of a Vice President who succeeds to the presidency.

The Twenty-second Amendment was a reaction to Franklin D. Roosevelt's election to an unprecedented four terms as president, but presidential term limits had long been debated in American politics.                                          

now you can mark brain hope this