One chapter ending writer's cutting (7)
I believe the answer is:
acerbic
'cutting' is the definition.
(I've seen this before)
'one chapter ending writer's' is the wordplay.
'one' becomes 'ace' ('ace' can be a synonym of 'one'**).
'ending' suggests the final letters.
'writer' becomes 'bic' (kind of pen).
The last letter of 'chapter' is 'r'.
'ace'+'r'+'bic'='ACERBIC'
(Other definitions for acerbic that I've seen before include "Tasting sour or caustic in speech" , "Astringent in tone" , "tart" , "Harsh and sharp in speech" , "Tasting bitter; forthright" .)