The term clean bill is used in two basic ways:
A bill that has been or is to be reintroduced with all of the changes from the amendments to the original bill written into the new bill to remove the necessity to consider the agreed-upon amendments from the original bill separately
U.S. Senate Definition
Generally, after a committee has amended legislation, the chairman may be authorized by the panel to assemble the changes and what remains unchanged from the original bill and then reintroduce everything as a clean bill. A clean bill may expedite Senate action by avoiding separate floor consideration of each committee amendment.