Close friend in good part (6)
I believe the answer is:
ending
'close' is the definition.
(I know that close can be written as ending)
'friend in good part' is the wordplay.
'part' indicates a hidden word.
'ENDING' is hidden within 'friend in good'.
(Other definitions for ending that I've seen before include "Finale" , "Closure" , "Putting a stop to" , "Armageddon?" , "ultimately" .)