Spirit generously opened by party-giver (5)
I believe the answer is:
ghost
'spirit' is the definition.
(spirit can mean a ghost)
'generously opened by party-giver' is the wordplay.
'generously opened' becomes 'g' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'by' is a charade indicator (letters next to each other).
'party-giver' becomes 'host' (I've seen this in another clue).
'g'+'host'='GHOST'
Can you help me to learn more?
(Other definitions for ghost that I've seen before include "who has a haunting act?" , "Spectre, wraith" , "Phantom" , "Spirit of the dead" , "Supernatural apparition" .)