Currency invested in support for plant, a hot one (7)
I believe the answer is:
cayenne
'plant a hot one' is the definition.
The answer and definition can be both plants as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'currency invested in support' is the wordplay.
'currency' becomes 'yen' (Japanese currency).
'invested in' is an insertion indicator.
'support' becomes 'cane' (I can't justify this - if you can you should give a lot more credence to this answer).
'yen' going inside 'cane' is 'CAYENNE'.
'for' acts as a link.
Can you help me to learn more?
(Other definitions for cayenne that I've seen before include "Hot red spice" , "Pungent red pepper" , "Capital of French Guiana - spicy red pepper" , "Kind of pepper" , "Spice from dried chillis" .)