The bird is angry, to begin with (8)
I believe the answer is:
redstart
'the bird' is the definition.
(type of bird)
'angry to begin with' is the wordplay.
'angry' becomes 'red' (someone may go red when angry).
'to' means one lot of letters go next to another.
'begin with' becomes 'start' (synonyms. I am not sure about the 'with' bit.).
'red'+'start'='REDSTART'
'is' acts as a link.
Can you help me to learn more?
(Other definitions for redstart that I've seen before include "Songbird" , "One sings" , "Half of 1D [GAME OR BIRD]" , "bird from Europe" , "Flier" .)