The most common and most likely answer to this crossword clue is the 3 letter word RUB
I've seen this crossword clue in The Daily Telegraph
R
U
B
More clues leading to the result RUB
- Polish friend back filled with a tattoo
- Polish gemstone lacking finish
- Difficulty chipping end off stone
- Polish problem
- Wipe food, not good
- Polish stone endlessly
- Difficulty promoting Battenburg cakes
- Rus in urbe? Not quite: clearing ugly ruins is the difficulty
- Numb bottom following half-hour back massage
- First thing for batsman after game is massage
Buddy explains!

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 RUB mean?
RUB noun- An act of rubbing.
- A difficulty or problem.
- A quip or sarcastic remark.
- In the game of crown green bowls, any obstacle by which a bowl is diverted from its normal course.
- Any substance designed to be applied by rubbing.
- To move (one object) while maintaining contact with another object over some area, with pressure and friction.
- To rub something against (a second thing).
- To be rubbed against something.
- To spread a substance thinly over; to smear.
- To move or pass with difficulty.
- To scour; to burnish; to polish; to brighten; to cleanse; often with up or over.
- To hinder; to cross; to thwart.
- (bowls) To touch the jack with the bowl.