Belief in money available (6)
I believe the answer is:
credit
I believe this is a double definition.
'belief' is the first definition.
(thesaurus)
'money available' is the second definition.
'in' acts as a link.
(Other definitions for credit that I've seen before include "good character" , "Positive balance in account" , "Money available for a client to borrow" , "Add (an amount) to an account" , "In this, you have money in the bank" .)