Former article and manuscript used for tests (5)
I believe the answer is:
exams
'for tests' is the definition.
('exam' can be a synonym of 'test')
'former article and manuscript' is the wordplay.
'former' becomes 'ex'.
'article' becomes 'a' (indefinite article).
'and' means one lot of letters go next to another.
'manuscript' becomes 'ms' (abbreviation for manuscript).
'ex'+'a'+'ms'='EXAMS'
'used' acts as a link.
(Other definitions for exams that I've seen before include "summer term commitment?" , "Tests, in short" , "Set of exercises evaluating knowledge (abbr)" , "Tests for students" , "School tests" .)