Easing of tensions (4)
I believe the answer is:
thaw
'easing of tensions' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for thaw that I've seen before include "What - melt like snow?" , "Become liquid" , "Become less stiff, more relaxed" , "(Of snow) start to melt" , "Begin to melt" .)