The most common and most likely answer to this crossword clue is the 5 letter word TOOTH
I've seen this crossword clue in The Daily Telegraph
T
O
O
T
H
More clues leading to the result TOOTH
- Cog, for example, excessively tough on the outside
- Peg overly thin? Not half!
- Canine possibly loves being in dry hotel
- Fang forming part of tattoo – thug’s?
- Fang forming part of tattoo there
- Maybe canine’s landmark birthday – extra stroke to head called for
- Taste for drilling and extraction
- Something of horn: hard, bonelike item
- Nipper excessively slight, lacking inches
- Canine, maybe, starts to trail one’s other terriers happily
Buddy explains!

The straight part
We know that "Canine" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case canine = tooth.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 TOOTH mean?
TOOTH noun- A hard, calcareous structure present in the mouth of many vertebrate animals, generally used for eating.
- A sharp projection on the blade of a saw or similar implement.
- A projection on the edge of a gear that meshes with similar projections on adjacent gears, or on the circumference of a cog that engages with a chain.
- A projection or point in other parts of the body resembling the tooth of a vertebrate animal.
- A pointed projection from the margin of a leaf.
- The rough surface of some kinds of cel or other films that allows better adhesion of artwork.
- Liking, fondness (compare toothsome).
- An irreducible component of a comb that intersects the handle in exactly one point, that point being distinct from the unique point of intersection for any other tooth of the comb.
- To provide or furnish with teeth.
- To indent; to jag.
- To lock into each other, like gear wheels.