One should exit refinery? It's related to the smell (9)
I believe the answer is:
olfactory
'related to the smell' is the definition.
I can't judge whether this definition defines the answer.
'one should exit refinery? it's' is the wordplay.
'one' becomes 'i' (Roman numeral).
'should exit' indicates named letters should be taken away.
'refinery?' becomes 'oil' (oil refinery is a kind of refinery).
'it's' becomes 'factory' (I can't explain this - if you can you should give a lot more credence to this answer).
'oil' with 'i' taken out is 'ol'.
'ol'+'factory'='OLFACTORY'
Can you help me to learn more?
(Other definitions for olfactory that I've seen before include "Dealing with smells" , "Pertaining to the sense of smell" , "Fool Tracy (anag) - relating to the sense of smell" , "Detecting scent" , "concerned with smell" .)