A treatment for ten apparently starting lunch (6)
I believe the answer is:
iodine
'a treatment' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe there's an association between them I don't understand?
'ten apparently starting lunch' is the wordplay.
'ten' becomes 'IO' (IO resembles d0).
'apparently starting lunch' becomes 'dine' (I can't justify this - if you can you should give a lot more credence to this answer).
'io'+'dine'='IODINE'
'for' acts as a link.
Can you help me to learn more?
(Other definitions for iodine that I've seen before include "Solution of a halogen in ethyl alcohol used on wounds as an antiseptic" , "Infamous tablets in case of a nuclear emergency" , "Antiseptic found in seaweed" , "Element used in medicine, photography and dyes" , "Mild antiseptic" .)