Substantial growth roughly doubled with ending of embargo (5)
I believe the answer is:
cacao
'substantial growth' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'roughly doubled with ending of embargo' is the wordplay.
'roughly' becomes 'ca'.
'doubled' says to double the letters.
'with' says to put letters next to each other.
'ending of' says to take the final letters.
The last letter of 'embargo' is 'o'.
'ca' doubled is 'caca'.
'caca'+'o'='CACAO'
Can you help me to learn more?
(Other definitions for cacao that I've seen before include "Tropical tree, the source of chocolate" , "Tree from which chocolate is made" , "Tree yielding chocolate" , "Tree supplying chocolate" , "Plant" .)