Live with a songbird! Go! (4,2)
I believe the answer is:
beat it
'go' is the definition.
(phrase used to tell someone to go away)
'live with a songbird' is the wordplay.
'live' becomes 'be' (synonyms).
'with' means one lot of letters go next to another.
'songbird' becomes 'tit' (tit is a type of songbird).
'be'+'a'+'tit'='BEAT IT'
(Other definitions for beat it that I've seen before include "Sling your hook!" , "Scram, get lost" , "make off furtively" , "Make off hastily" , "Slang order to go away, get lost" .)