Have a bit of fun with a bird abroad (4,5)
I believe the answer is:
lark about
'have a bit of fun with a bird abroad' is the definition.
I can't judge whether this defines the answer.
'fun with a bird abroad' is the wordplay.
'fun' becomes 'lark' (what a lark).
'with' is a charade indicator (letters next to each other).
'bird' becomes 'b' (this might be a standard abbreviation of which I'm unaware).
'abroad' becomes 'out' (abroad can mean away or out).
'lark'+'a'+'b'+'out'='LARK ABOUT'
Can you help me to learn more?
(Another definition for lark about that I've seen is " indulge in horseplay".)