Bird heading off hound (5)
I believe the answer is:
eagle
'bird' is the definition.
(eagle is a kind of bird)
'heading off hound' is the wordplay.
'heading off' means to remove the first letter.
'hound' becomes 'beagle' (beagle is a kind of hound).
'beagle' with its initial letter taken away is 'EAGLE'.
(Other definitions for eagle that I've seen before include "A birdie (or better!)" , "The bald one is a US symbol" , "High-flyer" , "Valuable piece" , "It may soar" .)