Possible Clues:

• Leading colt entering race - that's a sure thing
• Popular breath mint
• Sure thing (colloq.)
• Dick Francis book, ''Dead ___''
• Part of C.P.A.: Abbr.
• In short for sure
• Notarized doc., e.g.
• Dick Francis book ''Dead ___''
• Sure thing, in short
• Birth doc., e.g.