The most common and most likely answer to this crossword clue is the 11 letter word IMAGINATION
I've seen this crossword clue in The Times
I
M
A
G
I
N
A
T
I
O
N
Buddy explains!

The straight part
We know that "wit" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case wit = imagination.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 IMAGINATION mean?
IMAGINATION noun- The image-making power of the mind; the act of mentally creating or reproducing an object not previously perceived; the ability to create such images.
- Particularly, construction of false images; fantasizing.
- Creativity; resourcefulness.
- A mental image formed by the action of the imagination as a faculty; something imagined.