Writing openings of six chapters, getting upset about books (8)
I believe the answer is:
scribble
'writing' is the definition.
(scribble is a kind of writing)
'openings of six chapters getting upset about books' is the wordplay.
'openings of' indicates taking the first letters (I've seen 'opening' mean this).
'getting' says to put letters next to each other.
'upset' becomes 'rile' (to rile is to annoy or upset).
'about' means one lot of letters goes inside another.
'books' becomes 'BB' (an abbreviation for book written twice).
The first letters of 'six chapters' is 'sc'.
'rile' going around 'bb' is 'ribble'.
'sc'+'ribble'='SCRIBBLE'
(Other definitions for scribble that I've seen before include "Write illegibly" , "Dash off" , "Untidy writing" , "Scrawl" , "Write quickly and/or badly" .)