Spirited meeting in the main, delightful after one departs (6)
I believe the answer is:
seance
'spirited meeting' is the definition.
(I've seen this before)
'main delightful after one departs' is the wordplay.
I cannot really see how this works, but
'main' could be 'sea' (the main is an old name for the sea) and 'sea' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
'in the' acts as a link.
Can you help me to learn more?
(Other definitions for seance that I've seen before include "Meeting held by a medium" , "Meeting to contact the spirits of the dead" , "Spiritualist's sitting" , "Spiritualist meeting, all hold hands" , "Medium's session" .)