Shape of playing field introducing confusion (9)
I believe the answer is:
rectangle
'shape' is the definition.
(rectangle is a kind of shape)
'playing field introducing confusion' is the wordplay.
'playing field' becomes 'rec' (short for recreation ground).
'introducing' is a charade indicator (letters next to each other).
'confusion' becomes 'tangle' (tangle is a kind of confusion**).
'rec'+'tangle'='RECTANGLE'
'of' acts as a link.
(Other definitions for rectangle that I've seen before include "Four sides involved in this" , "Four-sided figure" , "regular sort of figure" , "box" , "Figure on plane" .)