Vegetable substance in sarsaparilla (3)
I believe the answer is:
sap
'vegetable substance' is the definition.
'sap' can be an answer for 'substance' (sap is a kind of substance). I'm unsure of the 'vegetable' bit.
'in sarsaparilla' is the wordplay.
'in' indicates a hidden word.
'SAP' is hidden in the letters of 'sarsaparilla'.
Can you help me to learn more?
(Other definitions for sap that I've seen before include "It's plant juice, idiot" , "trench used in siege" , "Plant's fluid" , "Moisture in wood of a tree" , "Weak foolish person" .)