Those calming things down for 23 down and 20 down at school

'those calming things down for 23 down and 20 down' is the definition.
I don't know anything about this answer so I can't judge whether this works.

'school' is the wordplay.
I cannot really understand how this works, but
'school' could be 's' and 's' is found within the answer.
The remaining letters 'peacekeeper' is a valid word which might be clued in a way I don't understand.
This may be the basis of clue (or it may be nonsense).

'at' acts as a link.

Can you help me to learn more?