Graceful long-necked bird (4)
I believe the answer is:
swan
'graceful long-necked bird' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for swan that I've seen before include "Large, web-footed bird" , "Mute, whooper or Bewick's bird" , "Large water bird" , "black, in 7th" , "Large aquatic bird" .)