The most common and most likely answer to this crossword clue is the 10 letter word BILINGUIST
I've seen this crossword clue in The Guardian
B
I
L
I
N
G
U
I
S
T
More clues leading to the result BILINGUIST
Buddy explains!

The straight part
We know that "Two-tongued individual" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case two-tongued individual = bilinguist.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.