Endures temperature — bitterly cold — at breaking point (4,5)
I believe the answer is:
last straw
'breaking point' is the definition.
(as in the straw that broke the camel's back)
'endures temperature bitterly cold' is the wordplay.
'endures' becomes 'lasts' ('last' can be a synonym of 'endure').
'temperature' becomes 't' (abbreviation).
'bitterly cold' becomes 'raw' (I've seen this in another clue).
'lasts'+'t'+'raw'='LAST STRAW'
'at' is the link.
(Other definitions for last straw that I've seen before include "Downfall of the laden camel" , "too much to bear?" , "Back-breaking assignment" , "The one that breaks the camel's back" , "That which broke the camel's back?" .)