Faith in secret communication (10)
I believe the answer is:
confidence
I believe this is a triple definition!
'faith' is the first definition.
(thesaurus)
'in' is a link.
'secret' is the second definition.
(confidence is a kind of secret)
'communication' is the third definition.
(confidence is a kind of communication)
(Other definitions for confidence that I've seen before include "communication of faith" , "Trust" , "Shared secret - belief" , "conviction" , "courage" .)