Cousin of a heron (4)
I believe the answer is:
ibis
'cousin of a heron' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ibis that I've seen before include "Bird with long neck and legs and a curved bill" , "sacred creature of Egypt" , "may be sacred?" , "Storklike bird" , "seaside feeder?" .)