Extract Republican found inside bar (7)
I believe the answer is:
excerpt
'extract' is the definition.
(I know that extract can be written as excerpt)
'republican found inside bar' is the wordplay.
'republican' becomes 'R' (abbreviation).
'found inside' means one lot of letters goes inside another.
'bar' becomes 'except' (both can mean 'not including').
'r' going into 'except' is 'EXCERPT'.
(Other definitions for excerpt that I've seen before include "Passage cut" , "Cutting" , "Selected passage from larger work" , "Sample of work" , "A passage or quotation from" .)