Artist got into scientist's room using the door, they say, in Canada (8)
I believe the answer is:
labrador
'in canada' is the definition.
(I know that Labrador is a is part of Newfoundland and Labrador)
'artist got into scientist's room using the door' is the wordplay.
'artist' becomes 'RA' (Royal Academician, member of Royal Academy of Arts).
'got into' indicates putting letters inside.
'scientist's room' becomes 'lab' (laboratory).
'using the door' becomes 'dor' (I can't explain this - if you can you should believe this answer much more).
'lab'+'dor'='labdor'
'ra' put into 'labdor' is 'LABRADOR'.
'they say' is the link.
This may not be correct. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for labrador that I've seen before include "Retriever dog or Canadian region" , "Region of NE Canada, or a retriever dog" , "Coastal region of eastern Canada" , "Spaniard who works" , "One that may have gone out with the guns" .)