Herb makes money here! (4)
I believe the answer is:
mint
'herb' is the definition.
(I know that mint is a type of herb)
'money here' is the wordplay.
'money' becomes 'm' (abbreviation in economics).
'here' becomes 'int' (I can't justify this - if you can you should believe this answer much more).
'm'+'int'='MINT'
'makes' is the link.
Can you help me to learn more?
(Other definitions for mint that I've seen before include "Fragrant herb" , "sweet herb" , "Where money is made by the government" , "lots of money" , "Large sum of money" .)