Not the first to stalk wading bird (4)
I believe the answer is:
rail
'wading bird' is the definition.
(rail is a kind of wading bird)
'not the first to stalk' is the wordplay.
'not the first' means to remove the first letter.
'to stalk' becomes 'trail' (I've seen this before).
'trail' with its initial letter taken off is 'RAIL'.
(Other definitions for rail that I've seen before include "Mode of transport; bar" , "The Iron Horse road" , "Water bird; bar" , "Waterside bird; part of track" , "Horizontal bar - bird - complain" .)