Chart-topping book written about love, perhaps (7)
I believe the answer is:
emotion
'love perhaps' is the definition.
(love is a kind of emotion)
'chart-topping book written about' is the wordplay.
'chart topping' becomes 'noi' (I can't justify this - if you can you should give a lot more credence to this answer).
'book' becomes 'tome' (a tome is a book).
'written about' shows that the letters should be reversed in order.
'noi'+'tome'='noitome'
'noitome' in reverse letter order is 'EMOTION'.
Can you help me to learn more?
(Other definitions for emotion that I've seen before include "Feeling such as joy, sorrow and fear" , "Intense feeling" , "Strong feeling as of love or hate" , "Strong feeling of joy, fear etc" , "E.g. fear, hate etc." .)