Pensioner reflected about opening in game (8)
I believe the answer is:
pachinko
'game' is the definition.
(pachinko is a kind of game)
'pensioner reflected about opening' is the wordplay.
'pensioner' becomes 'oap'.
'reflected' says the letters should be written in reverse.
'about' is an insertion indicator.
'opening' becomes 'chink' (chink is a kind of opening**).
'oap' back-to-front is 'pao'.
'pao' placed around 'chink' is 'PACHINKO'.
'in' acts as a link.
(Other definitions for pachinko that I've seen before include "Pinball machine" , "Japanese form on pinball" .)