One considering the Universe dispersing stoic’s gloom (11)
I believe the answer is:
cosmologist
'one considering the universe' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'dispersing stoic's gloom' is the wordplay.
'dispersing' is an anagram indicator.
'stoics'+'gloom'='stoicsgloom'
'stoicsgloom' with letters rearranged gives 'COSMOLOGIST'.
Can you help me to learn more?
(Another definition for cosmologist that I've seen is " One studying the universe".)