Get ready for school (4)
I believe the answer is:
prep
I believe this clue is a double definition.
'get ready' is the first definition.
(thesaurus)
'school' is the second definition.
(prep school is a kind of school)
'for' is the link.
(Other definitions for prep that I've seen before include "School work done outside lessons" , "warm-up race" , "Homework (abbr.)" , "Homework (abbrev.)" .)