Compromise with contented spiritualist (5,6)
I believe the answer is:
happy medium
'compromise' is the definition.
(I've seen this in another clue)
'with contented spiritualist' is the wordplay.
'with' is a charade indicator (letters next to each other).
'contented' becomes 'happy' (glad means contented or happy).
'spiritualist' becomes 'medium' (synonyms).
'happy' next to 'medium' is 'HAPPY MEDIUM'.
(Other definitions for happy medium that I've seen before include "Sensible middle way" , "pleased spiritualist" , "satisfied spirited interpreter" , "avoidance of extremes" , "Sensible middle course" .)