Break even in other school, initially (9)
I believe the answer is:
elevenses
'break' is the definition.
(I've seen this before)
'even in other school initially' is the wordplay.
'in' means one lot of letters goes inside another.
'other' becomes 'else' ('else' can be a synonym of 'other').
'initially' indicates taking the first letters.
The initial letter of 'school' is 's'.
'even' put into 'else' is 'elevense'.
'elevense'+'s'='ELEVENSES'
(Other definitions for elevenses that I've seen before include "Early drink" , "Morning snack" , "Mid-morning refreshment" , "energy getting second break" , "Mid-morning break" .)