Extreme cold, suggesting a big problem? (3,2,3,7)
I believe the answer is:
tip of the iceberg
'a big problem?' is the definition.
I know nothing about this answer so I cannot tell whether it can be defined by this definition.
'extreme cold' is the wordplay.
I cannot really understand how this works, but
'cold' could be 'ice' (I've seen this before) and 'ice' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
'suggesting' acts as a link.
Can you help me to learn more?
(Another definition for tip of the iceberg that I've seen is " hint of a much bigger problem".)