Gull relative (4)
I believe the answer is:
tern
'gull relative' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for tern that I've seen before include "Seagull" , "Fork-tailed relative of the gull" , "Winger" , "Small gull with forked tail" , "Pay rent for seabird" .)