Flier's revised rent (4)
I believe the answer is:
tern
'flier's' is the definition.
(type of bird)
'revised rent' is the wordplay.
'revised' is an anagram indicator.
'rent' with letters rearranged gives 'TERN'.
(Other definitions for tern that I've seen before include "Seabird, sounds like become sour" , "Gull-like seabird" , "Pay rent for seabird" , "Long-winged aquatic bird" , "Rent out the bird" .)