Possible Clues:

• Become converted
• Boil with anger before match, maybe, but understand
• Change to the better storm lamp
• Rise with dawn? Have an epiphany
• Come to understand
• Realise one's mistake, when switched on?
• Rage at answer to this clue, then have penny-drop moment
• Be very angry, then frivolous — change for the better?
• Gain sudden understanding