No ordeal disrupted Renaissance polymath (8)
I believe the answer is:
leonardo
'renaissance polymath' is the definition.
(Leonardo da Vinci)
'no ordeal disrupted' is the wordplay.
'disrupted' is an anagram indicator.
'no'+'ordeal'='noordeal'
'noordeal' anagrammed gives 'LEONARDO'.
(Other definitions for leonardo that I've seen before include "Da Vinci's name" , "US actor, - DiCaprio" , "Great Italian artist ........ da Vinci" , "Great painter of the Mona Lisa, . . . . . . . . da Vinci" , ". . . . . . . . da Vinci (Renaissance genius)" .)