Shape of class? (4)
I believe the answer is:
form
I believe this is a double definition.
'shape' is the first definition.
('form' can be a synonym of 'shape')
'class?' is the second definition.
('form' can be a synonym of 'class')
'of' acts as a link.
(Other definitions for form that I've seen before include "Part of school" , "A class in a school or a hare's lair" , "Hare's home - something to be filled in" , "Configuration; type" , "Class in a school, or the shape of something" .)