Bird dog cut by evil lad (4,5)
I believe the answer is:
bald eagle
'bird' is the definition.
(bald eagle is a kind of bird)
'dog cut by evil lad' is the wordplay.
'dog' becomes 'beagle' (beagle is a kind of dog).
'cut by' means one lot of letters goes inside another.
'evil' indicates anagramming the letters.
'lad' with letters rearranged gives 'ald'.
'beagle' enclosing 'ald' is 'BALD EAGLE'.
(Other definitions for bald eagle that I've seen before include "National emblem of the USA" , "N. American bird" , "Flier" , "US national bird" , "National bird of the USA" .)