The most common and most likely answer to this crossword clue is the 5 plus 8 letter word CHAIN REACTION
I've seen this crossword clue in The Sunday Telegraph
C
H
A
I
N
R
E
A
C
T
I
O
N
More clues leading to the result CHAIN REACTION
- Series about lawsuit that is self- sustaining once started
- Series of events caused by a car on thin ice crashing
- Row over allergy that could get out of control
- Restrict soldiers before battle, producing series of events
- Work of nuclear scientist or a technician, possibly
- Restrain tendency to oppose nuclear process?
- Sequence inevitably following flush?
- Moving a car on thin ice, one thing leads to another
Buddy explains!
The straight part
We know that "Work of nuclear scientist" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case work of nuclear scientist = chain reaction.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.