Illumination from old BBC radio programme (5)
I believe the answer is:
light
'illumination' is the definition.
(synonyms)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for light that I've seen before include "Fair" , "Eminent person" , "bulb" , "Blonde" , "What smoker may be requesting" .)