Do document, toe the line (7)
I believe the answer is:
conform
'toe the line' is the definition.
(I've seen this before)
'do document' is the wordplay.
'do' becomes 'con' (both can mean to defraud).
'document' becomes 'form' (form is a kind of document).
'con'+'form'='CONFORM'
(Other definitions for conform that I've seen before include "Comply with accepted rules" , "Agree" , "Follow the crowd" , "Match" , "Run with the pack" .)