Passage runs into bar (7)
I believe the answer is:
excerpt
'passage' is the definition.
(excerpt is a kind of passage)
'runs into bar' is the wordplay.
'runs' becomes 'r' (cricket abbreviation).
'into' indicates putting letters inside.
'bar' becomes 'except' (both can mean 'not including').
'r' put within 'except' is 'EXCERPT'.
(Other definitions for excerpt that I've seen before include "Passage selected from a book" , "Selection, extract" , "Piece (of music or book)" , "A selection or passage from" , "Selected passage from larger work" .)