Devastating force split a party (7)
I believe the answer is:
tornado
'devastating force' is the definition.
'split a party' is the wordplay.
'split' becomes 'torn' (I've seen this in other clues).
'party' becomes 'do' (do is a kind of party).
'torn'+'a'+'do'='TORNADO'
(Other definitions for tornado that I've seen before include "Dreadful blow" , "Major storm" , "Whirling storm" , "great deal of wind" , "Violent rotating windstorm" .)