Novel, we hear, about university detective and bespectacled bachelor – not bad! (5,4)

'bad' is the definition.
I don't know anything about this answer so I cannot judge whether this works.

'novel we hear about university detective and bespectacled bachelor not' is the wordplay.
I cannot really see how this works, but
'novel' could be 'book' and 'book' is found in the answer.
'about' could be 'a' (abbreviation in Chambers) and 'a' is found within the answer.
'university' could be 'u' (abbreviation for university) and 'u' is located in the answer.
'detective' could be 'di' (Detective Inspector abbreviation) and 'di' is found within the answer.
'not' could be 'o' (I've seen this in other clues) and 'o' is located in the answer.
No letters remain.
This explanation may well be incorrect...

Can you help me to learn more?