Connection to spy (4)
I believe the answer is:
bond
I believe this is a double definition.
'connection' is the first definition.
(I know that bond is a type of connection)
'to spy' is the second definition.
(James Bond)
(Other definitions for bond that I've seen before include "Certificate of debt" , "Affiliation" , "Written promise" , "Fictional agent; link" , "James . . . . aka 007" .)