The most common and most likely answer to this crossword clue is the 8 letter word STEARATE
S
T
E
A
R
A
T
E
Buddy explains!
The straight part
We know that "Salt" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case salt = stearate.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does STEARATE mean?
STEARATE noun- Any salt or ester of stearic acid.