The most common and most likely answer to this crossword clue is the 8 letter word KRAKATOA
I've seen this crossword clue in The Guardian
K
R
A
K
A
T
O
A
More clues leading to the result KRAKATOA
- Volunteers in fine rescue vessel recalled a scene of huge explosion
- A blast from the past, one pulled by puller, we hear?
- When exchanged, he pulls seasonal novelty, reportedly
- State rescue vessel comes back to a massive explosion
- It’s okay, not odd, to follow broadcast of knockout Big Bang episode?
- Narrow fissure a trailer reported in volcanic island
- Politician leaves Takoma Park to reform island
- On the radio, crack a toe on a volcanic island that disappeared
- Volcanic island has half-monster king and a tailless amphibian
- Two kings supplying alias to a largely defunct island
Buddy explains!
The straight part
We know that "A blast from the past" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case a blast from the past = krakatoa.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.