Subject recalled books and photo (5)
I believe the answer is:
topic
'subject' is the definition.
('topic' can be a synonym of 'subject')
'recalled books and photo' is the wordplay.
'recalled' says the letters should be written backwards.
'books' becomes 'ot' (Old Testament).
'and' says to put letters next to each other.
'photo' becomes 'pic' (I've seen this before).
'ot' in reverse letter order is 'to'.
'to'+'pic'='TOPIC'
(Other definitions for topic that I've seen before include "Subject (of, eg, speech)" , "Subject matter of a conversation or discussion" , "Subject (of speech, etc)" , "Subject (eg, of text)" , "Something to discuss" .)