Having done really well, was radiant (5)
I believe the answer is:
shone
'was radiant' is the definition.
(I've seen this in another clue)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for shone that I've seen before include "Excelled; glowed" , "did brilliantly" , "Gleamed" , "Radiated, emitted light" , "Gave off light" .)