The most common and most likely answer to this crossword clue is the 11 letter word DIRECTORIES
I've seen this crossword clue in The Daily Telegraph
D
I
R
E
C
T
O
R
I
E
S
Buddy explains!

The straight part
We know that "Guides" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case guides = directories.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.
Crossword Answer definitions
DIRECTORIES noun- A list of names, addresses etc, of specific classes of people or organizations, often in alphabetical order or in some classification.
- A structured listing of the names and characteristics of the files on a storage device.
- A virtual container in a computer's file system, in which files and other directories may be stored. The files and subdirectories in a directory are usually related.