Satan makes a large number wicked (5)
I believe the answer is:
devil
'satan' is the definition.
(I know that Devil is a satan)
'a large number wicked' is the wordplay.
'a large number' becomes 'd' (five hundred in Roman numerals).
'wicked' becomes 'evil' (similar in meaning).
'd'+'evil'='DEVIL'
'makes' acts as a link.
(Other definitions for devil that I've seen before include "Lucifer" , "Imp" , "Coat spicily; do hackwork" , "Wicked person" , "Unsurpassed" .)