Possible Clues:

• Siege
• Ordered to get round secure barrier
• Officer on weekend consumed by Bowie in bar
• Bar musical type losing the head consumed by a bit of grass
• Nasty European retaining secure check
• Besiege
• Told to include security to prevent access
• Obstruction ordered with security device to be brought in
• Ordered security in city investment, perhaps
• Prevent(ion of) access and exit