Old fashioned quadrangle (6)
I believe the answer is:
square
I believe this clue is a double definition.
'old fashioned' is the first definition.
'quadrangle' is the second definition.
(square is a kind of quadrangle)
(Other definitions for square that I've seen before include "Old-fashioned - fix" , "Rectangle with equal sides" , "area of town" , "Stick-in-the-mud -- quadrangle" , "Level - shape - piazza - stuffy" .)