Reviewed IMAX exhibition, partly for test (4)
I believe the answer is:
exam
'test' is the definition.
(synonyms)
'reviewed imax exhibition partly' is the wordplay.
'reviewed' says the letters should be written in reverse.
'partly' indicates the answer is hidden within the clue.
'maxe' is hidden within 'imax exhibition'.
'maxe' back-to-front is 'EXAM'.
'for' acts as a link.
(Other definitions for exam that I've seen before include "paper" , "One might be taken for English" , "Students sit it" , "Something to sit" , "Test (abbr)" .)