Dubious young lady on a list (9)
I believe the answer is:
debatable
'dubious' is the definition.
(synonyms)
'young lady on a list' is the wordplay.
'young lady' becomes 'De'.
'on' means one lot of letters go next to another.
'a list' becomes 'batable' (I am not sure about this - if you are sure you should believe this answer much more).
'de'+'batable'='DEBATABLE'
Can you help me to learn more?
(Other definitions for debatable that I've seen before include "subject to discussion" , "Open to argument" , "Open to question" , "Dubious" , "Moot" .)