Smear second book excluded from promotional hype (4)
I believe the answer is:
blur
'smear' is the definition.
(synonyms)
'second book excluded from promotional hype' is the wordplay.
I cannot quite see how this works, but
'second' could be 'b' (B can mean second eg B-side) and 'b' is present in the answer.
The remaining letters 'lur' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
(Other definitions for blur that I've seen before include "Group - smudge" , "Britpop band - indistinct vision" , "Indistinct mark" , "Hazy or indistinct representation" , "Hazy patch" .)