Puzzle in game resolved (6)
I believe the answer is:
enigma
'puzzle' is the definition.
(thesaurus)
'in game resolved' is the wordplay.
'resolved' is an anagram indicator.
'in'+'game'='ingame'
'ingame' is an anagram of 'ENIGMA'.
(Other definitions for enigma that I've seen before include "Difficult problem" , "Gamine being a bit of a puzzle" , "Solution to mystery" , "German military cipher machine" , "Mysteriously puzzling person or thing" .)