Unmask Tories perhaps there and then (8)
I believe the answer is:
outright
'there and then' is the definition.
'unmask tories perhaps' is the wordplay.
'unmask' becomes 'out'.
'tories perhaps' becomes 'right'.
'out'+'right'='OUTRIGHT'
(Other definitions for outright that I've seen before include "Completely and thoroughly" , "Immediately; openly" , "Directly; without reservation" , "Absolute - utter" , "Complete; immediately" .)