Girl gets very bad cheap book (5-8)
I believe the answer is:
penny-dreadful
'cheap book' is the definition.
(I've seen this before)
'girl gets very' is the wordplay.
'girl' becomes 'penny' (woman's name).
'gets very' becomes 'dreadful' (I can't explain this - if you can you should give a lot more credence to this answer).
'penny'+'dreadful'='PENNY-DREADFUL'
'bad' is the link.
I am not very happy about this link. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for penny-dreadful that I've seen before include "Cheap storybook" , "Melodramatic paperback novel" , "Cheap melodramatic novel" , "Sensational paperback novel" , "Junior relation of the shilling shocker?" .)