Music on the old boat synonymous with The Cellar
I believe the answer is:
rock salt
'the cellar' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'music on the old boat synonymous' is the wordplay.
I cannot really understand how this works, but
'music' could be 'rock' (rock is a kind of music) and 'rock' is located in the answer.
The remaining letters 'salt' is a valid word which might be clued in a way I don't understand.
This may be the basis of clue (or it may be nonsense).
'with' acts as a link.
Can you help me to learn more?
(Other definitions for rock salt that I've seen before include "flavouring" , "Seasoning" , "Mineral NaC One" , "Mineral sodium chloride" , "condiment" .)