Reference book's chapter on critical politician (9)
I believe the answer is:
directory
'reference book's' is the definition.
(directory is a kind of reference book)
'chapter on critical politician' is the wordplay.
'chapter' becomes 'c' (abbreviation).
'on' is a charade indicator (letters next to each other).
'critical' becomes 'dire' (similar in meaning).
'politician' becomes 'tory' (term for a Conservative Party politician).
'c' put after 'dire' is 'direc'.
'direc'+'tory'='DIRECTORY'
(Other definitions for directory that I've seen before include "Book listing names of inhabitants, users etc" , "No longer 192 in Britain" , "Book listing phone numbers" , "See 5" , "Catalogue" .)