British nobles (5)
I believe the answer is:
earls
'british nobles' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for earls that I've seen before include "Lear's out for the flight of the nobility" , "members of the House of Lords" , "London exhibition centre" , "Peers of the realm" , "They're below marquess and above viscount" .)