Possible Clues:

• To start with it's too long to come to the boil (6)
• Sharp instrument found in magazine
• Narrow window for publication of research
• Incision implement
• Theatrical knife
• Narrow opening guarded by surveillance team
• Pointed window essential in theatre
• Medical journal named after a surgical knife, with “The”
• Give permission to include party piece - that's cutting edge in The Theatre?
• A narrow window with a pointed arch at the top