Blunder about Irish beast (7)
I believe the answer is:
giraffe
'beast' is the definition.
(giraffes are animals)
'blunder about irish' is the wordplay.
'blunder' becomes 'gaffe' (gaffe is a kind of blunder).
'about' means one lot of letters goes inside another.
'irish' becomes 'IR' (abbreviation for Irish).
'gaffe' enclosing 'ir' is 'GIRAFFE'.
(Other definitions for giraffe that I've seen before include "Long-necked animal" , "African native ruminating" , "Tallest beast" , "Tallest living quadruped" , "Tallest extant quadruped" .)