Tory gains cut by 60 per cent, dance! (5)
I believe the answer is:
conga
'cent dance' is the definition.
'conga' can be an answer for 'dance' (conga is a kind of dance). I am unsure of the 'cent' bit.
'tory gains cut by 60 per' is the wordplay.
'tory' becomes 'con' (abbreviation for Conservative).
'gains' is a charade indicator (letters next to each other).
'cut by 60' becomes 'g' (I can't justify this - if you can you should believe this answer much more).
'per' becomes 'a'.
'con'+'g'+'a'='CONGA'
(Other definitions for conga that I've seen before include "Party dance" , "Latin-American dance" , "Dance performed in line" , "Snaking Latin American dance" , "Lined-up dance" .)