A girl imprisoned for having wasted money (8)
I believe the answer is:
misspent
'wasted money' is the definition.
'misspent' can be an answer for 'wasted' (I've seen this before). I'm not sure about the 'money' bit.
'a girl imprisoned for' is the wordplay.
'a girl' becomes 'miss' (term of address for an unmarried woman).
'imprisoned for' becomes 'pent' (I am not sure about this - if you are sure you should believe this answer much more).
'miss'+'pent'='MISSPENT'
'having' is the link.
Can you help me to learn more?
(Other definitions for misspent that I've seen before include "Passed the time unwisely, as a youth perhaps" , "Squandered" , "wasted away?" , "troublesome youth?" , "having used money unwisely" .)