Clarke's is a great company that makes great shoes and these are no exception. I got these as a gift from my parents. My feet usually totter around the 10 to 10.5 range. I got the 10.5 originally and I definitely though they were too big. Now I have the 10 and they feel nice and snug. The design of the shoe adheres to your ankle in a comfortable way that gives you a close, comfortable fit.
So, if you have an in between sized foot, go with the smaller one.