My database includes all the Stevens that I have ever found in Taylor, Cortland County, NY and there is no Clarence. I have not seen the name RADLEY in Taylor either. The surname does not appear in all of Cortland County in either the 1925 state census index or 1880 federal census index for the County. What time period are you looking for? I have seen the name Radway in Truxton and Homer. Could that be what you are looking for?