Publisher’s description of obscure book (5)
I believe the answer is:
blurb
'publisher's description' is the definition.
(I've seen this before)
'obscure book' is the wordplay.
'obscure' becomes 'blur' (both can mean to vague or indistinct).
'book' becomes 'b' (abbreviation for book).
'blur'+'b'='BLURB'
'of' is the link.
(Other definitions for blurb that I've seen before include "Publisher's descrtion of book" , "Advertising spiel" , "Publisher's promotional description" , "Short description on a book, etc" , "Promotional statement, on book-cover say" .)