Black in Brest (4)
I believe the answer is:
'black in brest' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for noir that I've seen before include "(Of film or fiction) with bleak settings and cynical characters" , "Film featuring bleak settings and cynical characters" , "film genre" , "Dark in France, like brooding films of 40s and 50s" , "Kind of dark film" .)