From Longman Dictionary of Contemporary Englishthe tip of the icebergthe tip of the icebergPROBLEMa small sign of a problem that is much larger The reported cases of food poisoning are only the tip of the iceberg. → tip
Examples from the Corpus
the tip of the iceberg• But the irregular payments for which Stan Flashman's club were punished may only be the tip of the iceberg.• This glitch would prove but the tip of the iceberg.• And that could be just the tip of the iceberg as official monitoring picks up only a fraction of illegal pollution.• Investigators say the irregular campaign contributions may be just the tip of the iceberg.• This is just the tip of the iceberg here, these are ones she got last night.• Advertising, however, turned out to be only the tip of the iceberg.• Despite these praiseworthy efforts, only the tip of the iceberg has been noticeably affected.• However, revolutionary technological innovation represents only the tip of the iceberg.• But this was only the tip of the iceberg. 