To cram a wafer, maybe, with cold, solid mass (4,3)

'solid mass' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.

'to cram a wafer maybe with cold' is the wordplay.
I cannot really understand how this works, but
'cram' could be 'pack' (synonyms) and 'pack' is located in the answer.
'cold' could be 'ice' (I've seen this before) and 'ice' is present in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?