I’ve reached “P for Paint”? (7)
I believe the answer is:
impasto
'paint?' is the definition.
(impasto is a type of paint)
'i've reached p for' is the wordplay.
I cannot really see how this works, but
'p' is present in the answer.
'for' could be 'to' (eg both can mean 'in the opinion of') and 'to' is present in the answer.
This explanation may well be incorrect...
(Other definitions for impasto that I've seen before include "artist's application" , "Sort of paint" , "Slapping paint on" , "Thickly-applied paint" , "application of paint in this way" .)