As transmitted it signifies agreement (6)
I believe the answer is:
assent
'agreement' is the definition.
(I know that assent is a type of agreement)
'as transmitted' is the wordplay.
'transmitted' becomes 'sent' ('send' can be a synonym of 'transmit').
'as'+'sent'='ASSENT'
'it signifies' is the link.
This may not be correct. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for assent that I've seen before include "Express approval or agreement" , "Agree, acquiesce" , "Acquiesce, comply" , "Agree - concede" , "Okay" .)