The most common and most likely answer to this crossword clue is the 7 letter word ATISHOO
I've seen this crossword clue in The Guardian
A
T
I
S
H
O
O
More clues leading to the result ATISHOO
- Sound from hooter in retreat, is hooting!
- Heard in dispute: what calls for blessing?
- Explosion setting army back: I drive off
- A hankie picked up? Sound evidence of a cold
- Hearing this, we hear a hanky's required!
- Reaction, by the sound of it, when apartment evacuated and I go away!
- Explosion, after which children all fall down?
- Quick expulsion, by the sound of it, as a pack of lies reported?
- In dispute, heard report of expulsion
- Sound of hooter, it has gone off with two rings
Buddy explains!
The straight part
We know that "Explosion" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case explosion = atishoo.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.