Faith bound to be heard (5)
I believe the answer is:
trust
'faith' is the definition.
(I know that faith can be written as trust)
'bound to be heard' is the wordplay.
'bound' becomes 'trussed' (similar in meaning).
'to be heard' indicates a 'sounds like' (homophone) clue.
'trussed' sounds like 'TRUST'.
(Other definitions for trust that I've seen before include "Firm belief (in someone)" , "Accept reliability of" , "Firm belief (in another)" , "Have faith in, regard as reliable" , "Firm belief (in person)" .)