Possible Clues:

• muscular or concentrated
• A short right turn in the powerful singing
• Brand loyalty is expected of his admirers
• A little right turn in the singing but not by the week, by the sound of it
• Not, by the sound of it, for a week has there been such a little right turn in the singing
• Sounds as if it does not take a week to be like this (6)
• Inviolable
• Its hold would be safe but it would never be the beginning of 4 down
• Forceful strain, including Thatcher first and last
• Robust sort changed - subsequently no good