Shout of disapproval before king's arrest (4)
I believe the answer is:
book
'arrest' is the definition.
(book can informally mean to arrest)
'shout of disapproval before king's' is the wordplay.
'shout of disapproval' becomes 'boo' (I've seen this before).
'before' says to put letters next to each other.
'king' becomes 'k' (abbreviation for king in chess).
'boo'+'k'='BOOK'
(Other definitions for book that I've seen before include "Reserve;tome" , "Reserve; tome" , "Rebecca or Emma maybe" , "Leaves, bound" , "Reserve - volume" .)