Confident fool shaped rivet to a point (9)
I believe the answer is:
assertive
'confident' is the definition.
(I've seen this before)
'fool shaped rivet to a point' is the wordplay.
'fool' becomes 'ass' (both can mean a stupid person).
'shaped' indicates an anagram.
'to a point' becomes 'e' (compass point).
'rivet' anagrammed gives 'ertiv'.
'ass'+'ertiv'+'e'='ASSERTIVE'
(Other definitions for assertive that I've seen before include "Self-assured and positive" , "Forcefully confident" , "Confident, self-assured" , "Positive, dogmatic" , "Positively self-assured" .)