Appears to check a manuscript (5)
I believe the answer is:
seems
'appears' is the definition.
('seem' can be a synonym of 'appear')
'check a manuscript' is the wordplay.
'check' becomes 'see' (synonyms).
'a manuscript' becomes 'ms' (abbreviation for manuscript).
'see'+'ms'='SEEMS'
'to' acts as a link.
(Other definitions for seems that I've seen before include "Appears, looks" , "Gives a certain impression" .)