Key Stage One accommodates new class (8)
I believe the answer is:
elegance
'class' is the definition.
(thesaurus)
'key stage one accommodates new' is the wordplay.
'key' becomes 'e' (I've seen this in other clues).
'stage' becomes 'leg' ('leg' can be a synonym of 'stage').
'one accommodates new' becomes 'ance' (I can't justify this - if you can you should believe this answer much more).
'e'+'leg'+'ance'='ELEGANCE'
Can you help me to learn more?
(Other definitions for elegance that I've seen before include "Showing good taste in dress or style" , "Fashionable grace" , "Polish - distinction" , "Chic" , "Fine quality" .)