Get ready before father starts to reproach everyone (7)
I believe the answer is:
prepare
'get ready' is the definition.
(synonyms)
'before father starts to reproach everyone' is the wordplay.
'before' becomes 'pre' ().
'father' becomes 'pa' (pa can mean dad or father).
'starts to' suggests taking the first letters.
The first letters of 'reproach everyone' is 're'.
'pre'+'pa'+'re'='PREPARE'
(Other definitions for prepare that I've seen before include "Make ready or suitable" , "get ready for something new" , "study" , "Make (something) ready" , "Fit out" .)