Flyer has one advertisement
I believe the answer is:
bill
I believe this clue is a double definition.
'flyer' is the first definition.
(I know this)
'one advertisement' is the second definition.
(I know that bill is a type of advertisement)
'has' acts as a link.
(Other definitions for bill that I've seen before include "The fellow" , "Poster; statement" , "Chap" , "Account; beak" , "Poster; draft law" .)