Took exam again, extremely repetitive test (5)
I believe the answer is:
resat
'took exam again' is the definition.
(I've seen this before)
'extremely repetitive test' is the wordplay.
'extremely' says to hollow out the word (remove centre letters) (only the extremes of the word are used).
'test' becomes 'sat' (SAT is a type of exam).
'repetitive' with its centre removed is 're'.
're'+'sat'='RESAT'
(Other definitions for resat that I've seen before include "Took another chance to pass" , "went back to the paper" , "was tested again" , "did test again" , "Took (exam) again" .)