We have a name for tobacco (4)
I believe the answer is:
weed
'tobacco' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Perhaps you can see an association between them that I don't see?
'we have a name' is the wordplay.
'have' is a charade indicator (letters next to each other).
'a name' becomes 'ed' (short for edward).
'we'+'ed'='WEED'
'for' is the link.
Can you help me to learn more?
(Other definitions for weed that I've seen before include "nuisance in bed" , "Cannabis; feeble person" , "Work in garden" , "Wild unwanted plant - tobacco?" , "Marijuana (slang)" .)