Order treatment before the writer (9)
I believe the answer is:
prescribe
'order treatment' is the definition.
'prescribe' can be an answer for 'order' (synonyms). I am unsure of the 'treatment' bit.
'before the writer' is the wordplay.
'before' becomes 'pre' (prefix meaning 'before').
'the writer' becomes 'scribe' (scribe is a kind of writer).
'pre'+'scribe'='PRESCRIBE'
Can you help me to learn more?
(Other definitions for prescribe that I've seen before include "Lay" , "Recommend as beneficial" , "Order use of (medicine or other treatment)" , "Advise use of (medicine)" , "as doctor may order" .)