Money is a bait that takes many in (5)
I believe the answer is:
lucre
'money' is the definition.
(I know that lucre is a type of money)
'bait that takes many in' is the wordplay.
'bait' becomes 'lure' (synonyms).
'that takes' is an insertion indicator.
'many in' becomes 'c' (I am not sure about this - if you are sure you should believe this answer much more).
'lure' going around 'c' is 'LUCRE'.
'is a' is the link.
Can you help me to learn more?
(Other definitions for lucre that I've seen before include "Profit dishonestly obtained" , "tin" , "financial gain" , "benefits from crime" , "monetary gain" .)