It means a lot to the Poles (4)
I believe the answer is:
tons
'it means a lot' is the definition.
The definition suggests a singular noun which matches the answer.
'to the poles' is the wordplay.
'the poles' becomes 'NS' (North and South poles).
'to'+'ns'='TONS'
Can you help me to learn more?
(Other definitions for tons that I've seen before include "Loads (sl.)" , "A lot" , "Each is equivalent to 2240 pounds" , "Lots" .)