Showing courage with bold rant (5)
I believe the answer is:
brave
'showing courage' is the definition.
(I've seen this before)
'with bold rant' is the wordplay.
'with' means one lot of letters go next to another.
'bold' becomes 'b' (abbreviation).
'rant' becomes 'rave' (synonyms).
'b' put next to 'rave' is 'BRAVE'.
(Other definitions for brave that I've seen before include "Defy" , "Egg-shaped" , "Heroic, valiant" , "bottle?" , "Fine" .)