Piece of work runs into bar (7)
I believe the answer is:
excerpt
'piece of work' is the definition.
(I've seen this before)
'runs into bar' is the wordplay.
'runs' becomes 'r' (cricket abbreviation).
'into' means one lot of letters goes inside another.
'bar' becomes 'except' (both can mean 'not including').
'r' going inside 'except' is 'EXCERPT'.
(Other definitions for excerpt that I've seen before include "bit of work" , "Passage from literature or music" , "A selection or passage from" , "Sample of work" , "Piece (of music or book)" .)