Getting on one in crazy game (3,4)
I believe the answer is:
old maid
'game' is the definition.
(thesaurus)
'getting on one in crazy' is the wordplay.
'getting on' becomes 'old' ('getting on a bit' means 'old').
'one' becomes 'i' (Roman numeral).
'in' indicates putting letters inside.
'crazy' becomes 'mad' ('mad' can be a synonym of 'crazy').
'i' put within 'mad' is 'maid'.
'old'+'maid'='OLD MAID'
(Other definitions for old maid that I've seen before include "Singleton" , "Obsolete expression for elderly unmarried woman" , "Excessively cautious person" , "Miss" , "never taken from the shelf?" .)