Agree to confess (5)
I believe the answer is:
admit
This clue is a double definition.
'agree' is the first definition.
(thesaurus)
'confess' is the second definition.
(thesaurus)
'to' is the link.
(Other definitions for admit that I've seen before include "Grant entry to" , "Profess" , "Usher in" , "permit to come in" , "Confess (to something)" .)