The most common and most likely answer to this crossword clue is the 9 letter word EXFOLIATE
I've seen this crossword clue in Financial Times
E
X
F
O
L
I
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More clues leading to the result EXFOLIATE
Buddy explains!

The straight part
We know that "Scrub" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case scrub = exfoliate.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 EXFOLIATE mean?
EXFOLIATE verb- To remove the leaves from a plant.
- To remove a layer of skin, as in cosmetic preparation.
- To split into scales, especially to become converted into scales as the result of heat or decomposition.