Old pamphlet in passage (7)
I believe the answer is:
extract
'passage' is the definition.
(I know that extract is a type of passage)
'old pamphlet' is the wordplay.
'old' becomes 'ex' (prefix meaning former or onetime).
'pamphlet' becomes 'tract' (synonyms).
'ex'+'tract'='EXTRACT'
'in' is the link.
(Other definitions for extract that I've seen before include "Take or pull out - say a tooth" , "Passage selected from a larger work" , "Short excerpt" , "Remove - piece" , "Part" .)