Breed of cattle and Channel Island (8)
I believe the answer is:
guernsey
'breed of cattle and channel island' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for guernsey that I've seen before include "Lyric poem" , "Breed of cattle and a Channel Island" , "Second largest of Channel Islands" , "Second-largest Channel Island" , "One of the Channel Islands" .)