One maybe treating canine with biscuit, finally -- it ends barking (7)
I believe the answer is:
dentist
'one maybe treating canine' is the definition.
I can't tell whether this definition defines the answer.
'biscuit finally it ends barking' is the wordplay.
'finally' suggests the final letters.
'barking' indicates anagramming the letters ('barking' can informally mean mad).
The last letter of 'biscuit' is 't'.
't'+'it'+'ends'='titends'
'titends' with letters rearranged gives 'DENTIST'.
'with' acts as a link.
Can you help me to learn more?
(Other definitions for dentist that I've seen before include "Open wide for him" , "One who treats teeth" , "Professional practioner" , "Oral surgeon" , "Teeth treater" .)