The most common and most likely answer to this crossword clue is the 13 letter word THERMONUCLEAR
I've seen this crossword clue in The Times
T
H
E
R
M
O
N
U
C
L
E
A
R
Buddy explains!
The straight part
We know that "Sort of explosion" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case sort of explosion = thermonuclear.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 THERMONUCLEAR mean?
THERMONUCLEAR adjective- Of, or relating to the fusion of atomic nuclei at high temperatures.
- Of, or relating to the use of atomic weapons based on such fusion, especially as distinguished from those based on fission.