Rock salt found on a piece of bacon (6)
I believe the answer is:
basalt
'rock' is the definition.
(basalt is a kind of rock)
'salt found on a piece of bacon' is the wordplay.
I cannot quite understand how this works, but
'salt' could be 'sal' (I've seen this in other clues) and 'sal' is located in the answer.
'on' could be 'at' (I've seen this in other clues) and 'at' is found within the remaining letters.
'piece' could be 'b' (abbreviation for bishop) and 'b' is located 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?
(Other definitions for basalt that I've seen before include "Rock containing olivine" , "Dark fine-grained volcanic rock" , "rock from 2 [VOLCANO]" , "Commonest type of solidified lava; dense, dark grey and fine-grained" , "Black volcanic rock" .)