Some schoolteacher's suffering (4)
I believe the answer is:
ache
'suffering' is the definition.
(I've seen this before)
'some schoolteacher's' is the wordplay.
'some' indicates a hidden word (some of the parts of the word are used).
'ACHE' is hidden in the letters of 'schoolteachers'.
(Other definitions for ache that I've seen before include "agony" , "Suffer dull pain" , "Dull continuous pain" , "Dull steady pain" , "Each (anag.)" .)