Boris frantically pens article, it indicates pressure? (6)
I believe the answer is:
isobar
'it indicates pressure?' is the definition.
(line of pressure on a map)
'boris frantically pens article' is the wordplay.
'frantically' is an anagram indicator.
'pens' indicates putting letters inside.
'article' becomes 'a' (the indefinite article in English).
'boris' with letters rearranged gives 'isobr'.
'isobr' going around 'a' is 'ISOBAR'.
(Other definitions for isobar that I've seen before include "Contour" , "A Boris (anag.)" , "Meteorological line joining points of equal pressure" , "It appears on some maps" , "Line connecting points of equal air pressure" .)