Twister in a party comes after dithering (7)
I believe the answer is:
tornado
'twister' is the definition.
(term for a tornado)
'a party comes after dithering' is the wordplay.
'party' becomes 'do' (do can informally mean a party).
'comes after' is a charade indicator (letters next to each other).
'dithering' becomes 'torn' (I am not sure about this - if you are sure you should believe this answer much more).
'a'+'do'='ado'
'ado' after 'torn' is 'TORNADO'.
'in' is the link.
Can you help me to learn more?
(Other definitions for tornado that I've seen before include "Donator of fierce wind" , "Typhoon" , "Tempest'" , "RAF fighter; whirlwind" , "Severe wind" .)