Possible Clues:

• I can tell you who will win — keep it dark — there's a row about it
• Adviser of a sort
• Means to attract attention in row -- I'll give better advice
• Tout's two notes on theory regularly ignored
• Racecourse tout
• One who should be able to give better advice?
• Row involving rider and tense racecourse regular
• End for Becket, turbulent priest, one predicts
• Tout in time corrupted priest
• One giving wanted (or unwanted) betting advice