Very large bird, a kind without tail (7)
I believe the answer is:
titanic
'very large' is the definition.
(I've seen this before)
'bird a kind without tail' is the wordplay.
'bird' becomes 'tit' (tit is a kind of bird).
'kind' becomes 'nice' (I've seen this before).
'without tail' means to remove the last letter.
'nice' with its last letter taken off is 'nic'.
'tit'+'a'+'nic'='TITANIC'
(Other definitions for titanic that I've seen before include "Gigantic like a famous doomed liner" , "Very big and powerful" , "Ill-fated vessel" , "Ship sunk by iceberg" , "Twenty one [SHIP]" .)