Cool spell I learned by phone (3,3)
I believe the answer is:
ice age
This could be a double definition.
'cool spell' is the first definition.
(cool period of time)
'i learned by phone' is the second definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
Can you help me to learn more?
(Other definitions for ice age that I've seen before include "lengthy number?" , "Very cold epoch" , "'When glaciers covered the earth (3,3)'" , "Cold spell (a very long one!)" , "Glacial period" .)