Spirited session can upset the diocese around (6)
I believe the answer is:
seance
'spirited session' is the definition.
(session for communing with spirits)
'can upset the diocese around' is the wordplay.
'upset' indicates an anagram.
'the diocese' becomes 'see' (I've seen this in another clue).
'around' means one lot of letters goes inside another.
'can' anagrammed gives 'anc'.
'anc' put within 'see' is 'SEANCE'.
(Other definitions for seance that I've seen before include "Meeting held by a medium" , "Spiritualists meeting with medium" , "Session for spiritualists" , "Sitting with a medium" , "Medium's session" .)