So that's your game ... wearing old, jaunty headgear! (5,3)
I believe the answer is:
opera hat
'headgear' is the definition.
(I know that opera-hat is a type of high hat)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for opera hat that I've seen before include "Lid that collapses" , "Headgear to hear 14dn" , "that can be altered to flatter profile" , "collapsible accessory - atop him surely?" , "garment in theatre?" .)