Artist’s colour I left inside in a pot, possibly (3,5)
I believe the answer is:
oil paint
'artist's colour' is the definition.
(a painter might use oil paints)
'i left inside in a pot possibly' is the wordplay.
I cannot really understand how this works, but
'i' could be 'a' and 'a' is located in the answer.
'left' could be 'l' (common abbreviation) and 'l' is located in the answer.
'inside' could be 'in' and 'in' is found in the answer.
This explanation may well be incorrect...
(Other definitions for oil paint that I've seen before include "Lit piano (anag.)" , "Artist's medium" , "Artist's material" .)