Clue: Rogue in Conservative Party Political Broadcast, say (3)
Answer: CAD
Explanation: Definition: Rogue

**C** (Conservative) + **AD** (advertisement so "party political broadcast, say")
 

 
*For the benefit of non-Brits, party political broadcasts are short TV advertisements extolling the virtues of a particular party (or more often these days, gainsaying the policies of a rival party) which can be shown at any time, but which become more common on the run up to an election.