The Clue It reminds you of old flame?
The Answer EMBER
The word "ember" refers to a small piece of burning or glowing coal or wood from a fire. This connects to the idea of an "old flame," which is a term for a past romantic relationship. Just like an ember can remind you of a fire that once burned brightly, an old flame can evoke memories of love and passion. Therefore, "ember" perfectly fits the clue by symbolizing the lingering feelings from a past romance.