The most common and most likely answer to this crossword clue is the 10 letter word TOOTHBRUSH
I've seen this crossword clue in The Guardian
T
O
O
T
H
B
R
U
S
H
Buddy explains!
The straight part
We know that "Piece of gear to groom canines" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case piece of gear to groom canines = toothbrush.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 TOOTHBRUSH mean?
TOOTHBRUSH noun- A brush, used with toothpaste, for cleaning the teeth.
- To clean or scrub with a toothbrush.