Brightest star in Cygnus (5)
I believe the answer is:
deneb
'brightest star in cygnus' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for deneb that I've seen before include "Bright star in Cygnus" , "First magnitude star in Cygnus" , "Bright star; be end (anag.)" , "The star Alpha Cygni" , "Be Ned (anag) - brightest star in Cygnus" .)