Boast about tiff (4)
I believe the answer is:
crow
'boast' is the definition.
(to crow about something is to boast about it)
'about tiff' is the wordplay.
'about' becomes 'c' (abbreviation for 'circa').
'tiff' becomes 'row' (I've seen this in another clue).
'c'+'row'='CROW'
(Other definitions for crow that I've seen before include "Make sounds of pleasure as a baby does - or a bird" , "Common bird" , "Black bird; boast" , "Native American -- bird" , "Gloat" .)