The most common and most likely answer to this crossword clue is the 14 letter word ANAGRAMMATICAL
I've seen this crossword clue in The Sunday Telegraph
A
N
A
G
R
A
M
M
A
T
I
C
A
L
More clues leading to the result ANAGRAMMATICAL
Buddy explains!

The straight part
We know that "with resorted letters" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case with resorted letters = anagrammatical.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 ANAGRAMMATICAL mean?
ANAGRAMMATICAL adjective- Being or relating to an anagram.