Possible Clues:

• Nosy one might see through this kind of surgery
• Listening post?
• Aperture in lock - kind of surgery
• Sort of surgery that may cover a number of wards
• Essential and reportedly complete part of lock
• Surgery for the listener?
• Part of the lock at wharf, we hear's a dump
• Important part of golf course gets such surgery
• Opening in door - kind of surgery
• Yale has such a narrow entrance ot it