Quiet, egg-headed female (3)
I believe the answer is:
she
'female' is the definition.
('she' refers to a woman)
'quiet egg-headed' is the wordplay.
'quiet' becomes 'sh' (both can be said to tell someone to be quiet).
'egg-headed' becomes 'e' (this could be a standard abbreviation which I don't know about).
'sh'+'e'='SHE'
Can you help me to learn more?
(Other definitions for she that I've seen before include "way to refer to mare" , "1887 Rider Haggard novel" , "fiction" , "Rider's novel" , "That woman" .)