Symbol of good in ladies? (4)
I believe the answer is:
logo
'symbol' is the definition.
(logo is a kind of symbol)
'good in ladies?' is the wordplay.
'good' becomes 'g' (abbreviation).
'in' means one lot of letters goes inside another.
'ladies?' becomes 'loo' ('the ladies' is a type of loo or toilet).
'g' going within 'loo' is 'LOGO'.
'of' acts as a link.
(Other definitions for logo that I've seen before include "Company emblem or device" , "Emblem, trade-mark" , "Brand's emblem" , "Vigour; relish" , "Printed symbol as emblem of organisation" .)