The most common and most likely answer to this crossword clue is the 14 letter word CLASSIFICATORY
I've seen this crossword clue in The Sunday Telegraph
C
L
A
S
S
I
F
I
C
A
T
O
R
Y
Buddy explains!

The straight part
We know that "sorting things" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case sorting things = classificatory.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 CLASSIFICATORY mean?
CLASSIFICATORY adjective- Serving to classify.