Crossword clues for the word: FLAREUP The word FLAREUP has appeared as an answer to at least 5 crossword clues on different crossword puzzles. Crossword clues for FLAREUP Showing 1 to 5 of 5 results Clue(s) Erupt suddenly Erupt, as fighting Intensify (2) Recurrence of an old problem Sudden, hot surge: hyph. wd.