Pleasant fumes could make one cross (7)
I believe the answer is:
incense
This could be a double definition.
'pleasant fumes' is the first definition.
The answer and definition can be both substances as well as being singular nouns.
Perhaps there's an association between them I don't understand?
'make one cross' is the second definition.
The answer and definition can be both related to thinking as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'could' is the link.
Can you help me to learn more?
(Other definitions for incense that I've seen before include "Cause strong reaction" , "Make furious" , "that may be used in service" , "It produces a fragrant odour when burned" , "can cause strong emotion" .)