Confident males, modest, relinquishing power (8)
I believe the answer is:
cocksure
'confident' is the definition.
(similar in meaning)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for cocksure that I've seen before include "Very confident like male fowl" , "Arrogant" , "The fowl begins to be offensively certain." , "Irritatingly self-confident" , "Use crock to be confidently certain" .)