Tacky books dismissed by some peers (7)
I believe the answer is:
viscous
'tacky' is the definition.
(tacky can mean sticky or viscous)
'books dismissed by some peers' is the wordplay.
'books' becomes 'NT' (abbreviation for New Testament).
'dismissed by' is a deletion indicator.
'some peers' becomes 'viscounts' (viscount is a type of peer).
'viscounts' with 'nt' taken out is 'VISCOUS'.
(Other definitions for viscous that I've seen before include "'Glutinous, sticky (7)'" , "Thick and gluey, like heavy oil" , "Treacly" , "Gelatinous" , "Resistant to flow" .)