From Longman Dictionary of Contemporary Englishhave a flutterhave a flutterBritish English informalDSHDL to risk a small amount of money on the result of something such as a horse race SYN have a bet → flutter
Examples from the Corpus
have a flutter• I had a little flutter on the Grand National and won £5.• She should never have fluttered the way she did.• Journos are invited to have a flutter with the cash.• I'm not a heavy gambler, but I like to have a flutter from time to time. 