Perverts and drips oddly included in school tests (7)
I believe the answer is:
sadists
'perverts' is the definition.
(sadist is a kind of pervert)
'drips oddly included in school tests' is the wordplay.
'oddly' indicates alternate letters.
'included in' is an insertion indicator.
'school tests' becomes 'sats' (scholastic assessment tests in the UK).
The alternate letters of 'drips' are 'dis'.
'dis' put within 'sats' is 'SADISTS'.
'and' acts as a link.
(Other definitions for sadists that I've seen before include "Perverted pain-inflicters" , "They like to hurt" , "Brutes" , "deviants" , "They take pleasure form inflicting pain" .)