Rare breed of short-legged chiefly white terriers developed in Wales (8)
I believe the answer is:
sealyham
(Other definitions for sealyham that I've seen before include "5 [MANS BEST FRIEND]" , "Dog that rhymes with ..." , "A shy male (anag) - dog" , "Wire-haired terrier" , "Hay meals (anag) - kind of terrier" .)