Test no longer taking half a day (4)
I believe the answer is:
Here is my best explanation:
'test' is the definition.
('exam' can be a synonym of 'test')
'no longer taking half a day' is the wordplay.
'no longer' becomes 'ex'.
'taking' is a charade indicator (letters next to each other).
'half' means to take half the letters.
'a' becomes 'an'.
'day' becomes 'm' (I can't explain this - if you can you should believe this answer much more).
'an' halved is 'a'.
(Other definitions for exam that I've seen before include "One might be taken for English", "One taken by candidate", "paper", "End-of-course assessment", "Formal knowledge test", "Important test", "Written test", "Test of knowledge", "Brief test" and "Scholastic test".)