Tory ultimately organising a dance (5)
I believe the answer is:
conga
'dance' is the definition.
(I've seen this before)
'tory ultimately organising a' is the wordplay.
'tory' becomes 'con' (abbreviation for Conservative).
'ultimately' says to take the final letters.
The final letter of 'organising' is 'g'.
'con'+'g'+'a'='CONGA'
(Other definitions for conga that I've seen before include "Snaking Latin American dance" , "Latin American dance performed in single file" , "Latin American "follow-my-leader" dance" , "Line-dancing" , "Single-file dance" .)