Compromise with a contented spiritualist (5,6)
I believe the answer is:
happy medium
'compromise' is the definition.
(I've seen this in another clue)
'with a contented spiritualist' is the wordplay.
'with' means one lot of letters go next to another.
'a contented' becomes 'happy' (glad means contented or happy).
'spiritualist' becomes 'medium' (synonyms).
'happy'+'medium' is 'HAPPY MEDIUM'.
(Other definitions for happy medium that I've seen before include "satisfied spirited interpreter" , "Sensible middle course" , "Satisfactory compromise" , "pleased spiritualist" , "result of successful session with board?" .)