Mostly old photos capturing my topsy-turvy games (8)
I believe the answer is:
olympics
'games' is the definition.
(thesaurus)
'mostly old photos capturing my topsy-turvy' is the wordplay.
'mostly' means to remove the last letter.
'photos' becomes 'pics'.
'capturing' means one lot of letters goes inside another.
'topsy turvy' shows that the letters should be reversed in order.
'my' backwards is 'ym'.
'old' with its final letter taken off is 'ol'.
'ol'+'pics'='olpics'
'olpics' enclosing 'ym' is 'OLYMPICS'.
(Other definitions for olympics that I've seen before include "Quadrennial athletics meeting" , "Quadrennial games" , "Slim copy of the games" , "Four-yearly world games" , "Large athletic competition, held every four years" .)