It's really great being a bird! I can fly! (7)
I believe the answer is:
titanic
'it's really great' is the definition.
I can't tell whether this definition defines the answer.
'a bird i can fly' is the wordplay.
'a bird' becomes 'tit' (tit is a kind of bird).
'fly' is an anagram indicator.
'i'+'can'='ican'
'ican' is an anagram of 'anic'.
'tit'+'anic'='TITANIC'
'being' acts as a link.
Can you help me to learn more?
(Other definitions for titanic that I've seen before include "In act it became an ill-fated ship" , "Film success (1997) - ship disaster (1912)" , "Twenty one [SHIP]" , "Ship sunk by iceberg" , "Gigantic like doomed ocean liner" .)