Like milk, it's a natural product (5)
I believe the answer is:
latex
This clue could be a double definition.
'like milk' is the first definition.
'latex' can be an answer for 'milk' (thesaurus). I'm not sure about the 'like' bit.
'a natural product' is the second definition.
'latex' can be an answer for 'product' (I have seen 'Synthetic product ' mean 'latex' so perhaps 'product' could also mean 'latex'). I'm not sure about the 'a natural' bit.
'it's' is the link.
Can you help me to learn more?
(Other definitions for latex that I've seen before include "Tree fluid used to make rubber" , "Whitish milky fluid" , "Stretchy stuff" , "Milky sap from certain plants that coagulates on exposure to air" , "Liquid used in making rubber" .)