A classic language some ladies preserve (5)
I believe the answer is:
latin
'a classic language' is the definition.
'latin' can be an answer for 'language' (Latin is an example). I am unsure of the 'a classic' bit.
'some ladies preserve' is the wordplay.
'some ladies' becomes 'la' (I can't justify this - if you can you should believe this answer much more).
'preserve' becomes 'tin' (tinning is a kind of preserving).
'la'+'tin'='LATIN'
Can you help me to learn more?
(Other definitions for latin that I've seen before include "Learning it 'an honour' (Churchill)" , "Language of old Romans" , "Classical language" , "demanding subject" , "Language of old 8 down" .)