This is being able to smell odors that don’t have any kind of physical source. This could smell of the perfume or a cigar/cigarette smoke of someone alive or dead, used as a sign of their presence around in ethereal way.
When our sense of smell is strong and distinct, we may be drawn to working as a florist, a wine taster or a perfume fragrance creator.
I have experienced this clair far less than other clairs. Initial days of my spiritual journey, I used to get a whiff of fragrances such as lavender, rose, sandalwood. These are the times when I would feel very calm and peaceful.
Exercise to strengthen Clairlience (Clear Smelling)
Go to a park, try smelling various flowers and keep a mental note of it.
Next time when you visit the park take few of those varieties, smell them with your eyes closed and try to identify them.