Contract, as written in order (8)
I believe the answer is:
decrease
'contract' is the definition.
(I know that contract is a more specific form of the action decrease)
'as written in order' is the wordplay.
'written in' is an insertion indicator.
'order' becomes 'decree' (synonyms).
'as' going within 'decree' is 'DECREASE'.
(Other definitions for decrease that I've seen before include "Reduction" , "Go down" , "drop" , "Smooth" , "subsidence" .)