Believe in solvency (6)
I believe the answer is:
credit
I believe this is a double definition.
'believe' is the first definition.
(I know that believe is a is a more specific form of the action credit)
'solvency' is the second definition.
(thesaurus)
'in' acts as a link.
(Other definitions for credit that I've seen before include "it's on the cards?" , "Time allowed to pay" , "support for one with money problems" , "gives you a good reputation" , "Arrangement for deferred payments" .)