Wading bird with a curved bill (4)
(Other definitions for avocet that I've seen before include "Flier" , "Long-legged wading bird with upward-curving bill" , "ornithological specimen" , "Wading bird with upturned bill" , "Long-legged shorebird with upward-curving bill" .)
'wading bird with a curved bill' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ibis that I've seen before include "One has large bill" , "Sacred Egyptian bird" , "State of central US, capital Lincoln" , "I'm faced with big bill" , "Hotel group" .)