Revolting person in Hilaire Belloc (5)
I believe the answer is:
rebel
'revolting person' is the definition.
(I've seen this in another clue)
'in hilaire belloc' is the wordplay.
'in' indicates the answer is hidden within the clue.
'REBEL' can be found hidden inside 'hilaire belloc'.
(Other definitions for rebel that I've seen before include "James Dean was one without a cause" , "Oppose authority" , "Revolting person" , "Eg, Cade or Hereward" , "Do things differently" .)