Large wading bird (4)
'large wading bird' is the definition.
(I've seen this before)
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" , "Bird sacred in Ancient Egypt" , "Wading bird of tropical waters" , "Large wader" , "Eastern" .)
(Other definitions for flamingo that I've seen before include "Large pink bird" , "Pink wader" , "Tall wading bird" , "Pink wading-bird" , "Long-legged bird" .)