Twister in two minds before a party (7)
I believe the answer is:
tornado
'twister' is the definition.
(term for a tornado)
'in two minds before a party' is the wordplay.
'in two minds' becomes 'torn' (I've seen this before).
'before' says to put letters next to each other.
'party' becomes 'do' (do is a kind of party).
'torn'+'a'+'do'='TORNADO'
(Other definitions for tornado that I've seen before include "Funnelling wind" , "Violent twister" , "lot of wind" , "Hurricane" , "Type of cyclone" .)