Diminish — curtail (7)
I believe the answer is:
abridge
I believe this clue is a double definition.
'diminish' is the first definition.
(thesaurus)
'curtail' is the second definition.
(I've seen this before)
(Other definitions for abridge that I've seen before include "Abbreviate, shorten" , "Edit down" , "Shorten by using fewer words" , "Make a precis of" , "(US) cattle-pen" .)