Some characters again appear in long story (4)
I believe the answer is:
saga
'long story' is the definition.
(a saga is a long and complicated story)
'some characters again appear' is the wordplay.
'some' says the answer is hidden in the clue (some parts of the word are used).
'SAGA' is hidden in the letters of 'characters again appear'.
'in' is the link.
(Other definitions for saga that I've seen before include "Long involved tale" , "Epic story" , "Lengthy tale" , "A long adventurous story - it's a gas" , "Long heroic tale" .)