The most common and most likely answer to this crossword clue is the 9 letter word DREAMLIKE
I've seen this crossword clue in The Daily Telegraph
D
R
E
A
M
L
I
K
E
Buddy explains!

The straight part
We know that "Imagined" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case imagined = dreamlike.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 DREAMLIKE mean?
DREAMLIKE adjective- Like something from a dream; having a sense of vagueness, insubstantiality, or incongruousness.