Traditional story's conclusion on stage (6)
I believe the answer is:
legend
'traditional story's' is the definition.
(I've seen this before)
'conclusion on stage' is the wordplay.
'conclusion' becomes 'end' (end is a kind of conclusion).
'on' is a charade indicator (letters next to each other).
'stage' becomes 'leg' ('leg' can be a synonym of 'stage').
'end' after 'leg' is 'LEGEND'.
(Other definitions for legend that I've seen before include "Old yarn" , "Person who has become famous" , "Motto" , "Celebrity" , "Story that may be untrue" .)