Opposed to Conservative's capers (6)
I believe the answer is:
antics
'capers' is the definition.
('antic' can be a synonym of 'caper')
'opposed to conservative's' is the wordplay.
'opposed to' becomes 'anti' (I've seen this before).
'conservative's' becomes 'C's' (UK political abbreviation).
'anti'+'cs'='ANTICS'
(Other definitions for antics that I've seen before include "Absurd tricks or pranks" , "Movements intended to cause amusement" , "Cat's in (anag.)" , "Buffoonery" , "Absurd or foolish movements intended to amuse" .)