One gets cold and anxious, no end, when it's freezing (3,3)
I believe the answer is:
ice age
This could be a double definition.
'one gets cold and anxious no end' is the first definition.
I know that 'cold' relates to this answer.
'when it's freezing' is the second definition.
(freezing-cold period of time)
Can you help me to learn more?
(Other definitions for ice age that I've seen before include "Freezing era" , "Cold historic period" , "Glacial epoch" , "time long ago" , "Cold period for Earth" .)