Liquid that can be dark but put on pale (8)
I believe the answer is:
creosote
'liquid that can be dark but' is the definition.
The answer and definition can be both substances as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'on pale' is the wordplay.
I cannot quite understand how this works, but
'on' could be 're' (regarding) and 're' is present in the answer.
This explanation may well be incorrect...
'put' is the link.
Can you help me to learn more?
(Other definitions for creosote that I've seen before include "Dark oily liquid, preservative for wood" , "Wood preserver made from coal tar" , "Wood treatment" , "Oily, smelly wood preservative" , "Oily liquid preservative -- eco-store (anag)" .)