• under fire

• strike while the iron is hot

• leave a lot to be desired

• add fuel to the fire

• set the heather on fire

• a spare tire

• a live wire

• like a house on fire

• have one's wires crossed

• the iron hand in the velvet glove

• open fire on it

• hang fire

• have several irons in the fire

• sick and tired of it

• spread like wildfire

• a firebrand

• out of the frying-pan and into the fire

• the iron horse

• rule him with a rod of iron

• open fire

• play with fire

• fire away

• there's no smoke without fire

• rule with a rod of iron

• live wire

• the fat is in the fire

• a high flier

• baptism of fire