The most common and most likely answer to this crossword clue is the 9 letter word LANGUAGES
I've seen this crossword clue in The Daily Telegraph
L
A
N
G
U
A
G
E
S
More clues leading to the result LANGUAGES
Buddy explains!

The straight part
We know that "tongues" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case tongues = languages.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 LANGUAGES mean?
LANGUAGES noun- A body of words, and set of methods of combining them (called a grammar), understood by a community and used as a form of communication.
- The ability to communicate using words.
- A sublanguage: the slang of a particular community or jargon of a particular specialist field.
- The expression of thought (the communication of meaning) in a specified way; that which communicates something, as language does.
- A body of sounds, signs and/or signals by which animals communicate, and by which plants are sometimes also thought to communicate.
- A computer language; a machine language.
- Manner of expression.
- The particular words used in a speech or a passage of text.
- Profanity.
- To communicate by language; to express in language.
- A languet, a flat plate in or below the flue pipe of an organ.