Make last possible contents of cellar? (4,4)
I believe the answer is:
rock salt
'possible contents of cellar?' is the definition.
(as in a salt cellar)
'make last' is the wordplay.
I cannot quite see how this works, but
an anagram of 'last' is 'salt' which is within the answer.
The remaining letters 'rock' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for rock salt that I've seen before include "Mineral sodium chloride" , "Halite" , "mineral deposit" , "Mineral NaC One" , "Seasoning" .)