Turning cool in eg end of temperate epoch (9)
I believe the answer is:
oligocene
'epoch' is the definition.
(Oligocene is an example)
'turning cool in eg end of temperate' is the wordplay.
'turning' indicates anagramming the letters.
'end of' says to take the final letters.
The final letter of 'temperate' is 'e'.
'cool'+'in'+'eg'='coolineg'
'coolineg' is an anagram of 'oligocen'.
'oligocen'+'e'='OLIGOCENE'
(Other definitions for oligocene that I've seen before include "from an ancient time" , "Insects full of energy, one holds, in" , "Period when first primates appeared, ie, Cologne (anag.)" , "Ancient period" , "age long gone" .)