Dreadful book promotion? (3)
I believe the answer is:
bad
'dreadful' is the definition.
(similar in meaning)
'book promotion?' is the wordplay.
'book' becomes 'b' (abbreviation for book).
'promotion?' becomes 'ad' (short for advert).
'b'+'ad'='BAD'
(Other definitions for bad that I've seen before include "SECOND HALF OF 16" , "Ill" , "Spoiled or evil" , "Harmful" , "Wicked" .)