The courageous part of us (3)
I believe the answer is:
our
'of us' is the definition.
(I've seen this before)
'the courageous part' is the wordplay.
'part' indicates a hidden word.
'OUR' is hidden within 'courageous'.
(Other definitions for our that I've seen before include "Relating to us" , "''Now is the winter of ... discontent'' (Richard III)" , "group possession?" , "Belonging to us" , "Yours and mine" .)