From Longman Dictionary of Contemporary Englishit’s a safe/sure/fair bet (that)it’s a safe/sure/fair bet (that)spokenCERTAINLY/DEFINITELY used to say that something seems almost certain I think it’s a pretty safe bet that he’ll get the job. → bet
Examples from the Corpus
it’s a safe/sure/fair bet (that)• He may not fancy it, but it's a safe bet that he would be the first man to do it.• Since they're not, it's a fair bet that they show something she doesn't want you to know.• As soon as a board attempts to interfere with management tasks it's a fair bet that profits will decline. 