Iceland stops installing zero pressure indicators (7)
I believe the answer is:
isobars
'pressure indicators' is the definition.
(lines on meteorological maps)
'iceland stops installing zero' is the wordplay.
'iceland' becomes 'is'.
'stops' becomes 'bars'.
'installing' indicates putting letters inside (I've seen this in other clues).
'zero' becomes 'o'.
'is'+'bars'='isbars'
'isbars' enclosing 'o' is 'ISOBARS'.
(Other definitions for isobars that I've seen before include "What may be featured on map" , "Air boss (anag.)" , "Lines linking places of equal barometric pressure" , "Lines of equal atmospheric pressure" , "Map lines of equal pressure" .)