The most common and most likely answer to this crossword clue is the 7 letter word BEESWAX
I've seen this crossword clue in The Guardian
B
E
E
S
W
A
X
Buddy explains!

The straight part
We know that "polish" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case polish = beeswax.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 BEESWAX mean?
BEESWAX noun- A wax secreted by bees from which they make honeycomb; or, the processed form of this wax used in the manufacture of various goods.
- (mildly) “Business”, as in such phrases as mind your own beeswax and none of your beeswax.
- To polish with beeswax.