It's on the cards, we believe (6)
I believe the answer is:
credit
'believe' is the definition.
(I know that credit is a more specific form of the action the trust)
'it's on the cards we' is the wordplay.
I cannot quite see how this works, but
'on' could be 're' ('on' can be mean 'with reference to') and 're' is found within the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for credit that I've seen before include "Good reputation; tick" , "Favourable balance - belief" , "entry in cashbook" , "Side of an account for payments in" , "Believe the advance of money" .)