Bench in class (4)
I believe the answer is:
form
This clue is a double definition.
'bench' is the first definition.
(I've seen this before)
'class' is the second definition.
(form class is a kind of class)
'in' acts as a link.
(Other definitions for form that I've seen before include "Configuration; type" , "Visible shape, class" , "Establish" , "Home of a hare" , "Criminal record (colloq.)" .)