Glory in playing Sudoku endlessly (5)
I believe the answer is:
kudos
'glory' is the definition.
(thesaurus)
'playing sudoku endlessly' is the wordplay.
'playing' indicates an anagram.
'endlessly' means to remove the last letter.
'sudoku' with its last letter removed is 'sudok'.
'sudok' with letters rearranged gives 'KUDOS'.
'in' is the link.
(Other definitions for kudos that I've seen before include "Pats on the back" , "Praise and honours" , "Pat on the back" , "Prestige; recognition" , "Renown" .)