What’s done in panels that you can hinge, primarily? (7)
I believe the answer is:
diptych
'what's done in panels that you can hinge primarily?' is the definition.
I can't judge whether this definition defines the answer.
'done in panels that you can hinge primarily?' is the wordplay.
'primarily?' says to take the initial letters (I've seen 'primarily' mean this).
The initial letters of 'done in panels that you can hinge' is 'DIPTYCH'.
(Other definitions for diptych that I've seen before include "Painting on two folding panels (7)" , "Picture pair" , "Two-part painting" , "Painting on dual surface, that folds" , "Pair of paintings on two hinged panels" .)