The most common and most likely answer to this crossword clue is the 6 plus 7 letter word ORIENT EXPRESS
I've seen this crossword clue in The Times
O
R
I
E
N
T
E
X
P
R
E
S
S
More clues leading to the result ORIENT EXPRESS
Buddy explains!
The straight part
We know that "in which murder committed" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case in which murder committed = orient express.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.