Possible Clues:

• Where I bring pressure to bear like this to be forbidding
• Line on a barometric map
• One thus secure in the meteorologist's line
• Line on map showing barometric pressure
• Weather map word
• Like this I forbid the same pressure along it
• Weatherman's air pressure line
• I therefore stick line on the map
• Map line showing atmospheric pressure
• Unkempt Boris muffles answer — it shows constant pressure