Actor's rising skill supports old flame (5)
I believe the answer is:
extra
'actor's' is the definition.
(extra is a kind of actor)
'rising skill supports old flame' is the wordplay.
'rising' says the letters should be written in reverse (going up in a down clue).
'skill' becomes 'art' (I've seen this before).
'supports' is a charade indicator (letters next to each other) (bottom letters provide a support for the top ones).
'old flame' becomes 'ex' (I've seen this in other clues).
'art' backwards is 'tra'.
'tra' after 'ex' is 'EXTRA'.
(Other definitions for extra that I've seen before include "Additional - run - actor - newspaper edition" , "eg Wide; additional" , "entry on scorecard?" , "no ball perhaps" , "Left over" .)