Temperature on earth changing and last of life, in conclusion, is endangered (10)
I believe the answer is:
threatened
'is endangered' is the definition.
(I've seen this before)
'temperature on earth changing and last of life in conclusion' is the subsidiary indication.
'temperature on' becomes 'threat' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'earth' becomes 'e'.
'changing' indicates an anagram.
'last of' indicates one should take the final letters.
'conclusion' indicates one should take the final letters.
The last letter of 'and' is 'd'.
The final letters of 'life in' are 'en'.
'd'+'en'='den'
'den' with letters rearranged gives 'ned'.
'threat'+'e'+'ned'='threatened'
Can you help me to learn more?
(Other definitions for threatened that I've seen before include "Put at risk, endangered" , "Facing danger" , "Menaced" , "potentially facing extinction" , "browbeaten" .)