Depressing Bond's leader over breach in security (5)
I believe the answer is:
bleak
'depressing' is the definition.
(thesaurus)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for bleak that I've seen before include "Gloomy" , "Desolate, hopoeless" , "Cold and unwelcoming" , "Bare, inhospitable" , "Unpleasantly cold" .)