Finish off last five questions set for exam (4)
I believe the answer is:
test
'for exam' is the definition.
(synonyms)
'finish off last five questions set' is the wordplay.
'finish off' says to take the final letters (I've seen 'finishing off' mean this).
The final letters of 'last five questions set' are 'TEST'.
(Other definitions for test that I've seen before include "Sample" , "Trial - international game" , "Cricket match; exam" , "catch trout in it?" , "Exam to play international cricket" .)