Brave bishop, advanced in years (4)
I believe the answer is:
bold
'brave' is the definition.
('bold' can be similar in meaning to 'brave')
'bishop advanced in years' is the wordplay.
'bishop' becomes 'b' (abbreviation used in chess).
'advanced in years' becomes 'old' (I've seen this before).
'b'+'old'='BOLD'
(Other definitions for bold that I've seen before include "sort of face" , "Courageous, confident" , "Daring, maybe impudent" , "Like heavy type" , "Typeface with thick heavy lines" .)