Theft by the Tories? It’s a plot! (10)
I believe the answer is:
conspiracy
'a plot' is the definition.
(conspiracy is a kind of plot)
'theft by the tories?' is the wordplay.
'theft' becomes 'piracy' (piracy is a kind of theft).
'by' is a charade indicator (letters next to each other).
'the tories?' becomes 'cons' (I've seen this in other clues).
'piracy' after 'cons' is 'CONSPIRACY'.
'it's' is the link.
(Other definitions for conspiracy that I've seen before include "that involves plotting" , "This is intriguing" , "scheme" , "Plot" , "intrigue" .)