Day in babyish outfit not unknown for rowdy girl (7)
I believe the answer is:
ladette
'day in babyish outfit' is the definition.
The definition suggests a singular noun which matches the answer.
'not unknown for rowdy girl' is the wordplay.
I cannot really understand how this works, but
'girl' could be 'de' and 'de' is present in the answer.
The remaining letters 'latte' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for ladette that I've seen before include "Loutish female" , "Party girl?" , "Young woman who acts as badly as a man" , "boisterous madam" , "boozy girl" .)