Hard work gets paintings into book (8)
I believe the answer is:
toilsome
'hard work' is the definition.
'paintings into book' is the wordplay.
'paintings' becomes 'oils' (I've seen this before).
'into' indicates putting letters inside.
'book' becomes 'tome' (tome is a kind of book).
'oils' placed into 'tome' is 'TOILSOME'.
'gets' acts as a link.
(Other definitions for toilsome that I've seen before include "Needing much effort" , "needing much work" , "laborious" .)