Bird about to have an argument
I believe the answer is:
crow
'bird' is the definition.
(crow is a kind of bird)
'about to have an argument' is the wordplay.
'about' becomes 'c' (abbreviation for 'circa').
'to have' means one lot of letters go next to another.
'an argument' becomes 'row' (to row is to argue).
'c'+'row'='CROW'
(Other definitions for crow that I've seen before include "Large black bird" , "shout in triumph" , "Common bird" , "Black bird; brag" , "Boast gloatingly, American Indian" .)