Head of Supreme Court about to shred legal document (6)
I believe the answer is:
script
'legal document' is the definition.
(thesaurus)
'head of supreme court about to shred' is the wordplay.
'head of' suggests taking the first letters.
'court' becomes 'ct' (abbreviation used in road names).
'about' indicates putting letters inside.
'to shred' becomes 'rip' (I've seen this in another clue).
The first letter of 'supreme' is 's'.
'ct' placed around 'rip' is 'cript'.
's'+'cript'='SCRIPT'
(Other definitions for script that I've seen before include "letters" , "Text, of a play say" , "Text of play, film etc" , "Piece of handwriting" , "Write" .)