Enormous bird — a kind with no tail (7)
I believe the answer is:
titanic
'enormous' is the definition.
(I've seen this in another clue)
'bird a kind with no tail' is the wordplay.
'bird' becomes 'tit' (tit is a kind of bird).
'kind' becomes 'nice' (I've seen this before).
'with no tail' means to remove the last letter.
'nice' with its last letter taken away is 'nic'.
'tit'+'a'+'nic'='TITANIC'
(Other definitions for titanic that I've seen before include "Extremely large" , "like Oceanus" , "Of great force or power, like the ill-fated ship" , "Ill-fated liner" , "Great ocean liner sunk by iceberg" .)