Circle or square (5)
I believe the answer is:
shape
This clue is a double definition.
'circle' is the first definition.
(I know that circle is a more specific form of the action shape)
'square' is the second definition.
(I know that square is a more specific form of the action shape)
(Other definitions for shape that I've seen before include "Control development of" , "Mould into new phase" , "External form" , "Heaps (anag.)" , "'Figure, outline (5)'" .)