Working in Canada, drunk reveals a reptile (8)
I believe the answer is:
anaconda
'a reptile' is the definition.
(anaconda is a kind of reptile)
'working in canada drunk' is the wordplay.
'working' becomes 'on' (on can mean working or activated).
'in' means one lot of letters goes inside another.
'drunk' indicates anagramming the letters.
'canada' anagrammed gives 'anacda'.
'on' put within 'anacda' is 'ANACONDA'.
'reveals' is the link.
(Other definitions for anaconda that I've seen before include "One may put squeeze on" , "S. Am. constrictor snake" , "Large water snake" , "Water-boa" , "South American killer" .)