The time of the Big Freeze (6)
I believe the answer is:
iceage
'the' is the definition.
I can't judge whether this defines the answer.
'time of the big freeze' is the wordplay.
I cannot really see how this works, but
'time' could be 'age' (an age is a period of time) and 'age' is located in the answer.
'freeze' could be 'ice' (as in water turning into ice) and 'ice' is found within the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Another definition for iceage that I've seen is " Period of extreme cold".)