Faith expressed in being tied up (7)
I believe the answer is:
trussed
'being tied up' is the definition.
(I've seen this before)
'faith expressed' is the wordplay.
'faith' becomes 'trust' ('trust' can be a synonym of 'faith').
'expressed' indicates a 'sounds like' (homophone) clue.
'trust' sounds like 'TRUSSED'.
'in' is the link.
(Other definitions for trussed that I've seen before include "Tied up" , "with restrictions on members" , "Secured" , "Dusters (anag) - bound" , "Bound up tightly" .)