Rock band in first book (7)
I believe the answer is:
genesis
This clue is a double definition.
'rock band' is the first definition.
(I've seen this before)
'first book' is the second definition.
(first book of the Bible)
'in' is the link.
(Other definitions for genesis that I've seen before include "Creation" , "name of group" , "rock band" , "Birth, beginnings" , "Beginning the holy book" .)