Yearns to change each school (5)
I believe the answer is:
aches
'yearns' is the definition.
('ache' can be a synonym of 'yearn')
'change each school' is the wordplay.
'change' is an anagram indicator.
'school' becomes 'S'.
'each' is an anagram of 'ache'.
'ache'+'s'='ACHES'
'to' is the link.
(Other definitions for aches that I've seen before include "Dull persistent pains" , "Gives a dull pain" , "Constant pains" , "Dull prolonged pains" , "Continuous pains" .)