A dictionary of Confusable Phrases: More Than 10,000 Idioms and Collocations

fire fight • firefighting
fire fight—
1
. an exchange of fire between opposing units (as
distinct from close combat): Three soldiers have been killed
in a fire fight with separatist guerrillas. 2. the effort to extin-
guish or to check the spread of a fire: Several firefighters were
transported to the local hospital during the fire fight.
firefighting — = fire fight 2: We want to be your number one
stop for information on volunteer firefighting, training and
legislation.
fire-irons • firing-iron
fire-irons —utensils for a fireplace (as tongs, poker, and
shovel): The floor was spotless; the grate and fire-irons were
burnished bright, and the fire burnt clear.
Note: 
The compound does not correlate in meaning with the
expression irons in the fire—(usually in the phrase “have many
irons in the fire”) used of things requiring the attention at once:
A few months ago I just had too many irons in the fire, and
I hate that feeling. It was time to refocus some priorities…
firing-iron —an iron used in cauterizing a horse: When the
farrier has made his firing-iron red hot in his forge, he applies
the thinnest part to the horses skin.
fire line • line of fire
fire line —
1
. a strip of cleared or ploughed land intended to
check a forest fire: It became clear that the truck would survive
once it outsped the fire line. 2. a police barrier around a build-
ing on fire: It is the responsibility of the police department to
keep unauthorized persons outside this fire line.
line of fire —(also: firing line) 
1
. the path of a missile dis-
charged from a firearm: Large dugouts were built … so that
they were not directly in line of fire from enemy guns. 2. a
position where one is likely to come under attack, receive pun-
ishment, etc.: Modern art is the cause of much argument, so
the writer has placed himself in the line of fire between the
two sides.