Script producer has to check court document with Her Majesty (12)
I believe the answer is:
screenwriter
'script producer' is the definition.
(a screenwriter writes scripts for TV or film)
'to check court document with her majesty' is the wordplay.
'to check' becomes 'screen' (synonyms).
'court document' becomes 'writ' (I've seen this before).
'with' means one lot of letters go next to another.
'her majesty' becomes 'er' (Elizabeth Regina).
'screen'+'writ'+'er'='SCREENWRITER'
'has' acts as a link.
(Other definitions for screenwriter that I've seen before include "Film script author" , "One creating film script" .)