Vegetable extract of sarsaparilla (3)
I believe the answer is:
sap
'vegetable extract' is the 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?
'of sarsaparilla' is the wordplay.
'of' indicates the answer is hidden within the clue.
'SAP' is hidden within 'sarsaparilla'.
Can you help me to learn more?
(Other definitions for sap that I've seen before include "Enervate" , "Undermine; fool" , "dig tunnels" , "Gradually weaken (a person's strength)" , "Charlie" .)