He became proverbially rich from various sources (7)
I believe the answer is:
croesus
'he became proverbially rich' is the definition.
The definition suggests a singular noun which matches the answer.
'various sources' is the wordplay.
'various' indicates anagramming the letters.
'sources' with letters rearranged gives 'CROESUS'.
'from' is the link.
Can you help me to learn more?
(Other definitions for croesus that I've seen before include "Fabulously wealthy man" , "Rich old king" , "Proverbial rich man" , "One famously loaded" , "King of fabulous wealth" .)