Brunel thus does about-turn in well-mannered debate about government, say (10)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

I (Brunel, our crossword setter), then SIC (Latin for “thus” = an editor’s mark indicating that an apparent error is to be read as printed) reversed (doing an about-turn); all contained in POLITE (well-mannered). Politicise = to talk about something in political terms.