Rent out gull (4)
I believe the answer is:
tern
'gull' is the definition.
(I've seen this before)
'rent out' is the wordplay.
'out' is an anagram indicator (out can mean wrong or inaccurate).
'rent' is an anagram of 'TERN'.
(Other definitions for tern that I've seen before include "Winger" , "Seagull" , "Gull-like seabird" , "Rent out the bird" , "Seabird, sounds like become sour" .)