The most common and most likely answer to this crossword clue is the 10 letter word PROPHESIED
I've seen this crossword clue in The Sunday Telegraph
P
R
O
P
H
E
S
I
E
D
Buddy explains!

The straight part
We know that "told about in advance" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case told about in advance = prophesied.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
PROPHESIED verb- To speak or write with divine inspiration; to act as prophet.
- To predict, to foretell (with or without divine inspiration).
- To foreshow; to herald; to prefigure.
- To speak out on the Bible as an expression of holy inspiration; to preach.