Outstanding character ruined by one spy trial... (11)
I believe the answer is:
personality
'outstanding character' is the definition.
'personality' can be an answer for 'character' (I've seen this before). I am not certain of the 'outstanding' bit.
'ruined by one spy trial' is the wordplay.
'ruined by' indicates an anagram.
'one'+'spy'+'trial'='onespytrial'
'onespytrial' anagrammed gives 'PERSONALITY'.
Can you help me to learn more?
(Other definitions for personality that I've seen before include "Celebrity" , "(Distinctness of) character" , "Individual disposition" , "Distinctive character" , "Individual character" .)