Ad copy (5)
I believe the answer is:
blurb
'ad copy' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for blurb that I've seen before include "Publisher's promotional description" , "Publisher's write-up" , "Promotional text for a book" , "Publisher's promotional text" , "Publisher's descrtion of book" .)