Book someone who's got loaded (6)
I believe the answer is:
primer
'book' is the definition.
(primer is a kind of book)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for primer that I've seen before include "Elementary textbook" , "Initial coat of paint" , "Introductory textbook or first coat of paint" , "Basic teaching book" , "it might be used by one 7 [PAINTING]" .)