Nice socks, fancy, producing overconfidence (9)
I believe the answer is:
cockiness
'overconfidence' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'nice socks fancy' is the wordplay.
'fancy' is an anagram indicator.
'nice'+'socks'='nicesocks'
'nicesocks' anagrammed gives 'COCKINESS'.
'producing' is the link.
Can you help me to learn more?
(Other definitions for cockiness that I've seen before include "Swagger" , "Arrogance" .)