Getting everything out on holiday (8)
I believe the answer is:
vacation
'holiday' is the definition.
(I know that holiday can be written as vacation)
'getting everything out on' is the wordplay.
'getting' becomes 'va' (I can't justify this - if you can you should give a lot more credence to this answer).
'everything' becomes 'creation' (all of creation).
'out' indicates named letters should be taken away.
'on' becomes 're' (regarding).
'creation' with 're' removed is 'cation'.
'va'+'cation'='VACATION'
Can you help me to learn more?
(Other definitions for vacation that I've seen before include "Leisure time away from work" , "Leave" , "break" , "An American holiday" , "Holiday period" .)