Notice something protruding from bird (4)
I believe the answer is:
bill
I believe this clue is a double definition.
'notice' is the first definition.
(both can mean an advertisement)
'something protruding from bird' is the second definition.
(bill can mean a bird's beak)
(Other definitions for bill that I've seen before include "one settles with in America?" , "- - Clinton or Gates" , "Law proposal" , "informing of damage" , "Statute in draft before it becomes law" .)