Roman illumination? (6)
I believe the answer is:
candle
'roman illumination?' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
This is the entire clue.
Can you help me to learn more?
(Other definitions for candle that I've seen before include "Wax cylinder" , "A taper" , "Old form of illumination" , "that's wicked!" , "Measurement of light" .)