Romans insist on changing conveyance (12)
I believe the answer is:
transmission
'conveyance' is the definition.
(thesaurus)
'romans insist on changing' is the wordplay.
'on' says to put letters next to each other.
'changing' indicates an anagram.
'romans'+'insist'='romansinsist'
'romansinsist' anagrammed gives 'TRANSMISSION'.
(Other definitions for transmission that I've seen before include "The sending of a radio signal" , "A broadcast programme" .)