Be a bird — buzz off! (4,2)
I believe the answer is:
beat it
'buzz off' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.
'be a bird' is the wordplay.
'bird' becomes 'tit' (tit is a kind of bird).
'be'+'a'+'tit'='BEAT IT'
Can you help me to learn more?
(Other definitions for beat it that I've seen before include "Clear off!" , "Get going" , "Slang order to go away, get lost" , "Make off hastily" , "make off furtively" .)