The most common and most likely answer to this crossword clue is the 12 letter word IMPERSONATED
I've seen this crossword clue in The Daily Telegraph
I
M
P
E
R
S
O
N
A
T
E
D
Buddy explains!

The straight part
We know that "took off" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case took off = impersonated.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 IMPERSONATED mean?
IMPERSONATED verb- To pretend to be (a different person); to assume the identity of.
- To operate with the permissions of a different user account.
- To manifest in corporeal form; to personify.