Wading bird, black, is seen on island (4)
I believe the answer is:
ibis
'wading bird' is the definition.
(ibis is a kind of wading bird)
'black is seen on island' is the wordplay.
'black' becomes 'b' (abbreviation as in pencil hardness).
'seen on' means one lot of letters go next to another.
'island' becomes 'i' (geographical abbreviation).
'b'+'is'='bis'
'bis' after 'i' is 'IBIS'.
(Other definitions for ibis that I've seen before include "Large wading bird" , "Wading bird of warm regions" , "Retreat" , "Wading bird of tropical waters" , "Bird sacred in Ancient Egypt" .)