One personifying the beginning of depravity and wickedness (5)
I believe the answer is:
devil
'one personifying' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'beginning of depravity and wickedness' is the wordplay.
'beginning of' suggests taking the first letters.
'and' means one lot of letters go next to another.
'wickedness' becomes 'evil' (synonyms).
The initial letter of 'depravity' is 'd'.
'd'+'evil'='DEVIL'
'the' acts as a link.
Can you help me to learn more?
(Other definitions for devil that I've seen before include "Evil supernatural being" , "Imp" , "Old Nick, Satan" , "See 11" , "Lucifer" .)