Look that intimidates radiant person? (6)
I believe the answer is:
glower
'look that intimidates radiant person?' is the definition.
'glower' can be an answer for 'look' (glower is a kind of look). I am unsure of the rest of the definition.
'look that intimidates' is the wordplay.
'look' becomes 'glow' (glowing is a kind of looking).
'that intimidates' becomes 'er' (I am not sure about this - if you are sure you should believe this answer much more).
'glow'+'er'='GLOWER'
Can you help me to learn more?
(Other definitions for glower that I've seen before include "Look black" , "Frown" , "firefly?" , "Look hard and angrily" , "Angry stare" .)