Saw new books on the shelf (7)
I believe the answer is:
noticed
'saw' is the definition.
(I've seen this before)
'new books on the shelf' is the wordplay.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'books' becomes 'OT' (Old Testament).
'on the shelf' becomes 'iced' (I can't justify this - if you can you should believe this answer much more).
'n'+'ot'+'iced'='NOTICED'
Can you help me to learn more?
(Other definitions for noticed that I've seen before include "Detected" , "remarked" , "Observed or saw" , "Became aware of" , "Seen" .)