Paint in schoolbook? (6)
I believe the answer is:
primer
I believe this is a double definition.
'paint' is the first definition.
(I know that primer is a type of coat of paint)
'schoolbook?' is the second definition.
(I know that primer is a type of schoolbook)
'in' is the link.
(Other definitions for primer that I've seen before include "it might be used by one 7 [PAINTING]" , "Elementary text book" , "First school book" , "First coat - book" , "Educational book" .)