The most common and most likely answer to this crossword clue is the 11 letter word WESTMINSTER
W
E
S
T
M
I
N
S
T
E
R
More clues leading to the result WESTMINSTER
- With wit, Mrs T seen off in Parliament
- Point put by cleric renouncing one current Parliament
- School with church by East Street
- Witness term going badly in public school
- Parliament strewn with items unintelligible
- Parliament has divergent ways for landing in appalling new mire
- Parliament or the Church makes men twisters
- Items strewn about Parliament
- Where Brexit future is being decided by formulating its new terms
- Point above large church somewhere in central London
Buddy explains!

The straight part
We know that "School" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case school = westminster.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.