White heron (5)
I believe the answer is:
egret
'white heron' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for egret that I've seen before include "Water-bird, has plume" , "Wader with white plumage" , "Greet (anag) -- wading bird" , "White wading bird" , "one with plume" .)