Gave a heads-up is an expression used to describe the act of informing someone in advance about something. In this case, the crossword solutions for the term are ALERTED (7 letters) and warned (6 letters). ALERTED means to inform or notify someone of a potential danger or risk, while warned means to give someone a cautionary advice or admonition. Therefore, both words can be used interchangeably to describe the act of giving someone a heads-up.