The most common and most likely answer to this crossword clue is the 1 plus 9 plus 2 plus 7 letter word A TRANSPORT OF DELIGHT
I've seen this crossword clue in Financial Times
A
T
R
A
N
S
P
O
R
T
O
F
D
E
L
I
G
H
T
Buddy explains!
The straight part
We know that "Great happiness induced by Flanders omnibus?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case great happiness induced by flanders omnibus? = a transport of delight.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.