Especially U.S.: transferred use of the surname, originally a local name from any of the several places in England (for example, in Lancs., Staffs., Sussex, and W. Yorks.) named with Old English clǣg ‘clay’ + tūn ‘enclosure, settlement’.
English (mainly Yorkshire): habitational name from any of various places, for example in Durham and Yorkshire, so called from Old English scīr ‘bright’ + burna ‘stream’. (In southern English dialects, burna became modern bourne, and Sherborne in Dorset is one of several places so called.)