Number one accepts erring badly will get the bird (9)
I believe the answer is:
peregrine
'bird' is the definition.
(peregrine is a kind of bird)
'number one accepts erring badly will get' is the wordplay.
'number one accepts' becomes 'pee' (I am not sure about this - if you are sure you should believe this answer much more).
'badly' is an anagram indicator (letters in the wrong order).
'will get' means one lot of letters goes inside another.
'erring' is an anagram of 'regrin'.
'pee' going around 'regrin' is 'PEREGRINE'.
'the' acts as a link.
Can you help me to learn more?
(Other definitions for peregrine that I've seen before include "bird" , "Large falcon" , "Kind of falcon" , "Powerful falcon" .)