Girl on about style (5)
I believe the answer is:
class
'girl on about style' is the definition.
'class' can be an answer for 'style' (thesaurus). I'm unsure of the 'girl on about' bit.
'girl on about style' is the wordplay.
'girl' becomes 'lass' (lass is a kind of girl).
'on' means one lot of letters go next to another.
'about style' becomes 'c' (I can't justify this - if you can you should give a lot more credence to this answer).
'lass' after 'c' is 'CLASS'.
Can you help me to learn more?
(Other definitions for class that I've seen before include "pupils?" , "Group of students" , "sort" , "Set, category" , "Group - style" .)