Discreet page fronts filthy book collection (7)
I believe the answer is:
prudent
'discreet' is the definition.
('prudent' can be similar in meaning to 'discreet')
'page fronts filthy book collection' is the wordplay.
'fronts' suggests taking the first letters (I've seen 'front' mean this).
'filthy' becomes 'rude'.
'book collection' becomes 'nt' (New Testament).
The initial letter of 'page' is 'p'.
'p'+'rude'+'nt'='PRUDENT'
(Other definitions for prudent that I've seen before include "Thinking of the future" , "caution" , "not taking any risks?" , "Careful and sensible" , "Careful, circumspect" .)