Big-headed, very experienced and courageous (4)
I believe the answer is:
bold
'courageous' is the definition.
(similar in meaning)
'big-headed very experienced' is the wordplay.
I cannot quite see how this works, but
'experienced' could be 'old' (similar in meaning) and 'old' is present in the answer.
A single letter 'b' remains which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'and' is the link.
Can you help me to learn more?
(Other definitions for bold that I've seen before include "Like heavy type" , "Typeface with thick heavy lines" , "Brave" , "Daring, maybe impudent" , "sort of face" .)