Regime change in places with extremes of temperature (6)
I believe the answer is:
putsch
'regime change' is the definition.
(a putsch is a coup against a government)
'places with extremes of temperature' is the wordplay.
'places' becomes 'puts' ('put' can be a synonym of 'place').
'with' means one lot of letters go next to another.
'extremes of temperature' becomes 'C H' (abbreviations for cold and hot).
'puts'+'ch'='PUTSCH'
'in' is the link.
(Other definitions for putsch that I've seen before include "A sudden political rebellion" , "Sudden illegal acquisition of power" , "Coup d'etat" , "Violent revolt" , "Violent attempt to seize power" .)