Book about anger small and boring (8)
I believe the answer is:
tiresome
'boring' is the definition.
(I know that boring can be written as tiresome)
'book about anger small' is the wordplay.
'book' becomes 'tome' (a tome is a book).
'about' means one lot of letters goes inside another.
'anger' becomes 'ire' (ire is intense rage).
'small' becomes 's' (abbreviation - e.g. clothes size).
'ire'+'s'='ires'
'tome' going around 'ires' is 'TIRESOME'.
'and' is the link.
(Other definitions for tiresome that I've seen before include "wearing" , "Draggy - unamusing" , "Wearying" , "Is remote, being boring" , "Fatiguing, tedious" .)