What's brown and sticky? Bit of wood a canine left inside (7)
I believe the answer is:
treacle
'what's brown and sticky? bit' is the definition.
I can't tell whether this defines the answer.
'of wood a canine left inside' is the wordplay.
'of wood' becomes 'tree' (I can't explain this - if you can you should believe this answer much more).
'canine' becomes 'c' (dental abbreviation).
'left' becomes 'l' (common abbreviation).
'inside' is an insertion indicator.
'a'+'c'+'l'='acl'
'tree' enclosing 'acl' is 'TREACLE'.
Can you help me to learn more?
(Other definitions for treacle that I've seen before include "Sweet sticky syrup" , "Syrup-like substance" , "Sweet, black viscous substance" , "Dark viscous 11" , "Viscous liquid" .)