Figures out the tea's stirred, it's milky (5)
I believe the answer is:
latex
'it's milky' is the definition.
I can't judge whether this defines the answer.
'figures out the tea's stirred' is the wordplay.
'figures' becomes 'lx' (I can't explain this - if you can you should give a lot more credence to this answer).
'out' means one lot of letters goes inside another.
'stirred' is an anagram indicator.
'tea' with letters rearranged gives 'ate'.
'lx' placed around 'ate' is 'LATEX'.
Can you help me to learn more?
(Other definitions for latex that I've seen before include "Milky fluid produced by plants" , "Milky source of rubber" , "Milky sap of rubber tree" , "Milky fluid from poppies, rubber plants etc" , "white stuff" .)