The most common and most likely answer to this crossword clue is the 7 letter word VOLCANO
I've seen this crossword clue in The Daily Telegraph
V
O
L
C
A
N
O
More clues leading to the result VOLCANO
- Tailless rodent is able to settle by old source of vents
- Very cool, an active smoker?
- Oval cone not completely reshaped?
- Almost split up with a number lower down Mt Fuji?
- Book has the ability to offend for a start — might one blow one’s top?
- Coal, no scuttles? After five it’s probably covered in ash
- Left in very old tin, old type of firework
- Old instrumentaccompanying short song, say, in mountain hotspot?
- Book addresses prison love, it produces hot material
- A burning issue may arise from it
Buddy explains!
The straight part
We know that "type of firework" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case type of firework = volcano.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does VOLCANO mean?
VOLCANO noun- A vent or fissure on the surface of a planet (usually in a mountainous form) with a magma chamber attached to the mantle of a planet or moon, periodically erupting forth lava and volcanic gases onto the surface.
- A form of firework.