True from the time of Roman Empire origins (7)
I believe the answer is:
sincere
'true' is the definition.
(similar in meaning)
'from the time of roman empire origins' is the wordplay.
'from the time of' becomes 'since'.
'origins' indicates taking the first letters.
The first letters of 'roman empire' is 're'.
'since'+'re'='SINCERE'
(Other definitions for sincere that I've seen before include "Without deceit, genuine" , "Perfect" , "(Of person) genuine" , "natural?" , "Candid" .)