The most common and most likely answer to this crossword clue is the 10 letter word MANSCAPING
I've seen this crossword clue in The Guardian
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Buddy explains!
The straight part
We know that "grooming activity" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case grooming activity = manscaping.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 MANSCAPING mean?
MANSCAPING verb- To impose a shape on the landscape to suit humans.
- To trim or shave a male's hair, typically other than the hair atop and behind his head. The term applies most frequently to facial hair, including that of the eyebrows, ears, and nostrils; somewhat frequently to shoulders and back; less frequently to buttocks and pubes; infrequently to arms and legs.
- The practice of, or results from, trimming or shaving a male's hair, typically other than the hair atop and behind his head. The term applies most frequently to facial hair, including that of the eyebrows, ears, and nostrils; somewhat frequently to shoulders and back; less frequently to buttocks and pubes; infrequently to arms and legs.