Evil caste circulating a stoical philosophy (4,2,3)
I believe the answer is:
cest la vie
'a stoical philosophy' is the definition.
The definition suggests a singular noun which matches the answer.
'evil caste circulating' is the wordplay.
'circulating' is an anagram indicator.
'evil'+'caste'='evilcaste'
'evilcaste' with letters rearranged gives 'CEST LA VIE'.
Can you help me to learn more?
(Other definitions for cest la vie that I've seen before include "Whatever will be will be" , "There's nothing we can do about it!" , "Vets Alice (anag) - French expression of resignation" , "That's life for the French (1'3,2,3)" .)