Document is left after change (8)
I believe the answer is:
passport
'document' is the definition.
(passport is a kind of document)
'left after change' is the wordplay.
'left' becomes 'port' (left side of a ship - opposite of starboard).
'after' says to put letters next to each other.
'change' becomes 'pass' (passing is a kind of changing**).
'port' after 'pass' is 'PASSPORT'.
'is' acts as a link.
(Other definitions for passport that I've seen before include "Authorization to go abroad and return" , "Travel identification" , "one admits" , "entry permit?" , "Official document required for foreign travel" .)