Related Clues:

• First from optic in one's pub -- an indication of pressure?
• Pressure line
• A Boris (anag.)
• Make noise as animal that's faint
• I accordingly must join legal group on which pressure is constant
• I'm high-flying Brit in meteorological line
• Needing refilling
• Stuck-in-the-mud gear
• Pressure line like this found in one pub
• War zone that is right away from country's boundary
• Boris upset about article describing Met line
• Line of constant pressure
• Line on map in black -- I fly around it
• Deep, as a voice
• Meteorological contour