The most common and most likely answer to this crossword clue is the 8 letter word BRUSHING
I've seen this crossword clue in The Guardian
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Buddy explains!
The straight part
We know that "Groom’s job?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case groom’s job? = brushing.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 BRUSHING mean?
BRUSHING verb- To clean with a brush.
- To untangle or arrange with a brush.
- To apply with a brush.
- To remove with a sweeping motion.
- To touch with a sweeping motion, or lightly in passing.
- To clean one's teeth by brushing them.
- An instance of brushing.
- Brisk; light