The most common and most likely answer to this crossword clue is the 7 letter word PREQUEL
I've seen this crossword clue in The Guardian
P
R
E
Q
U
E
L
Buddy explains!
The straight part
We know that "it appears out of order" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case it appears out of order = prequel.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 PREQUEL mean?
PREQUEL noun- In a series of works, an installment that is set chronologically before its predecessor, especially the original narrative or (perhaps improper usage) any narrative work with at least one sequel.