Birds with S-shaped necks (6)
I believe the answer is:
egrets
'birds with s-shaped necks' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for egrets that I've seen before include "Greets in way of certain herons (" , "waders" , "White wading birds" , "Greets like certain herons" , "Kind of herons with long white feathers" .)