Most brave, better than all others, inwardly worn out? (7)
I believe the answer is:
'most brave' is the definition.
('bold' can be similar in meaning to 'brave')
'better than all others inwardly worn out?' is the wordplay.
'better than all others' becomes 'best'.
'inwardly' means one lot of letters goes inside another (I've seen this in other clues).
'worn out?' becomes 'old' (I've seen this in another clue).
'best' placed around 'old' is 'BOLDEST'.
(Other definitions for boldest that I've seen before include "most striking", "Most daring or naughty".)