Quiet individual was brilliant (5)
I believe the answer is:
shone
'was brilliant' is the definition.
(I've seen this in another clue)
'quiet individual' is the wordplay.
'quiet' becomes 'sh' (both can be said to tell someone to be quiet).
'individual' becomes 'one' (an individual is one person).
'sh'+'one'='SHONE'
(Other definitions for shone that I've seen before include "Gleamed" , "did brilliantly" , "Excelled; glowed" , "Sparkled" , "Radiated, emitted light" .)