Throw out fool scratching bottom in party (6)
I believe the answer is:
banish
'throw out' is the definition.
(banishing is a kind of throwing out)
'fool scratching bottom in party' is the wordplay.
'fool' becomes 'nit' (I've seen this before).
'scratching bottom' means to remove the last letter.
'in' is an insertion indicator.
'party' becomes 'bash' (term for a party or celebration).
'nit' with its last letter taken away is 'ni'.
'ni' placed into 'bash' is 'BANISH'.
(Other definitions for banish that I've seen before include "Exile (someone)" , "outlaw" , "Exile in ash-bin" , "Deport, exile" , "Cast out, ostracize" .)