Credit is tied up we're told (5)
I believe the answer is:
trust
'credit' is the definition.
(trust is a kind of credit)
'tied up we're told' is the wordplay.
'tied up' becomes 'trussed' ('truss' can be a synonym of 'tie up').
'we're told' indicates a 'sounds like' (homophone) clue.
'trussed' is a homophone of 'TRUST'.
'is' is the link.
(Other definitions for trust that I've seen before include "bank on" , "Firm belief (in someone/something)" , "Firm belief (in another)" , "Hope, expect" , "Believe" .)