The most common and most likely answer to this crossword clue is the 13 letter word PERPENDICULAR
I've seen this crossword clue in Independent
P
E
R
P
E
N
D
I
C
U
L
A
R
More clues leading to the result PERPENDICULAR
- Erect pillar half-heartedly with prudence abandoned
- Newly fitted up pad with recliner — in which one won’t be this!
- Upright piano, with arrangement of a prelude in C, right?
- In Cup red player, yard away, smashed upright
- Not the architectural style associated with Pisa’s tower?
- Normal American criminal harried car in Duel
Buddy explains!

The straight part
We know that "Normal" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case normal = perpendicular.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 PERPENDICULAR mean?
PERPENDICULAR noun- A line or plane that is perpendicular to another.
- A device such as a plumb line that is used in making or marking a perpendicular line.
- A meal eaten at a tavern bar while standing up.
- At or forming a right angle (to something).
- Exactly upright; extending in a straight line toward the centre of the earth, etc.
- Independent of or irrelevant to each other; orthogonal.