The most common and most likely answer to this crossword clue is the 4 letter word BOLD
I've seen this crossword clue in The Guardian
B
O
L
D
More clues leading to the result BOLD
- Fearless British getting on
- Bishop, experienced and fearless
- Enterprising bachelor getting on
- Brazen bachelor of advanced years
- Brave British veteran
- Striking leader of band, advanced in years
- Courageous chap embracing sovereign
- Intrepid orator’s dismissed during play
- Belgium’s veteran forward
- Person about fifty certainly not timid
Buddy explains!

The straight part
We know that "Courageous" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case courageous = bold.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does BOLD mean?
BOLD noun- A dwelling; habitation; building.
- Courageous, daring.
- Visually striking; conspicuous.
- (of typefaces) Having thicker strokes than the ordinary form of the typeface.
- Presumptuous, forward or impudent.
- Naughty; insolent; badly-behaved.
- Full-bodied.
- Pornographic; depicting nudity.
- Steep or abrupt.
- To make (a font or some text) bold.
- To make bold or daring.
- To become bold.