The most common and most likely answer to this crossword clue is the 11 letter word DISCERNMENT
I've seen this crossword clue in The Times
D
I
S
C
E
R
N
M
E
N
T
Buddy explains!

The straight part
We know that "Perception" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case perception = discernment.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 DISCERNMENT mean?
DISCERNMENT noun- The ability to distinguish; judgement.
- Discrimination.
- The ability to distinguish between things.
- The ability to perceive differences that exist.
- The condition of understanding.
- Aesthetic discrimination; taste, appreciation.
- Perceptiveness.
- The ability to make wise judgements; sagacity.
- Discretion in judging objectively.