Correct last word by director (5)
I believe the answer is:
amend
'correct' is the definition.
(amending is a kind of correcting)
'last word by director' is the wordplay.
'last word' becomes 'amen' (last word in a prayer).
'by' is a charade indicator (letters next to each other).
'director' becomes 'd'.
'amen'+'d'='AMEND'
(Other definitions for amend that I've seen before include "Make small improvements to" , "Revise" , "Make minor improvements to (something)" , "Rectify" , "Correct error, make minor alteration as to writing" .)