The company's deal with the government has brought 'cries/accusations of foul play' [=claims that there have been unfair or dishonest acts] from its competitors.
She is still missing, and the police now suspect that she may have been a victim of 'foul play'. [=that she may have been murdered or harmed in some way]
After leaving school she 'fell foul of' the law. [=she got into trouble with the law; she was arrested for committing a crime]
(..) I am thy father's spirit Doomed for a certain term to walk the night, and for the day confined to fast in fires... ...till the foul crimes done in my days of nature are burnt and purged away But that I am forbid to tell the secrets of my prison house, I could a tale unfold... (..)2015 Hamlet
(..) - Our duty to your honour - Your love as mine to you. Farewell All is not well. Would the night were come. 'fill then, sit still my soul Foul deeds will rise, though all the earth o'erwhelm them, to men's eyes My necessaries are embarked, farewell And sister, as the winds give benefit (..)2015 Hamlet