He doesn't think much of others (6)
I believe the answer is:
egoist
'he doesn't think much of others' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
This is the entire clue.
Can you help me to learn more?
(Other definitions for egoist that I've seen before include "Person with very a good opinion of himself" , "Selfish person" , "It goes around with conceited fellow" , "He puts himself first" , "Self-absorbed person" .)