Push good book as top-priority (6)
I believe the answer is:
urgent
'top-priority' is the definition.
(I've seen this in another clue)
'push good book' is the wordplay.
'push' becomes 'urge' (I've seen this in another clue).
'good book' becomes 'NT' (New Testament).
'urge'+'nt'='URGENT'
'as' acts as a link.
(Other definitions for urgent that I've seen before include "Earnest, insistent" , "Needing immediate action" , "Pressing, imperative" , "Extremely pressing" , "Demanding immediate attention" .)