The Collaborative International Dictionary of English v.0.48:

Clydesdale \Clydes"dale\, n.
   One of a breed of heavy draft horses originally from
   Clydesdale, Scotland. They are about sixteen hands high and
   usually brown or bay.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

Clydesdale
    n 1: heavy feathered-legged breed of draft horse originally from
         Scotland