Alan is not revising subjects (9)
I believe the answer is:
nationals
'subjects' is the definition.
('national' can be a synonym of 'subject')
'alan is not revising' is the wordplay.
'revising' is an anagram indicator.
'alan'+'is'+'not'='alanisnot'
'alanisnot' is an anagram of 'NATIONALS'.
(Other definitions for nationals that I've seen before include "countrymen" , "Natives" , "newspapers" , "Country folk" , "Subjects" .)