Curiosity in charge for borrowing money (8)
I believe the answer is:
interest
This clue is a double definition.
'curiosity' is the first definition.
(I know that curiosity can be written as interest)
'charge for borrowing money' is the second definition.
(I've seen this before)
'in' acts as a link.
(Other definitions for interest that I've seen before include "Concern or pastime" , "Pursuit" , "Stake; concern deeply" , "Sense of concern or curiosity" , "Proceeds" .)