A burning issue is a topic or problem that is of great importance and urgency. The crossword solutions for this term are ARSON (5 letters), ASH (3 letters), LAVA (4 letters), and AFIRE (5 letters). ARSON is the criminal act of deliberately setting fire to property, while ASH is the residue left after something has been burned. LAVA is molten rock expelled by a volcano during an eruption, and AFIRE is an adjective used to describe something that is burning.